Buying Guide · Updated November 2026
Best Indoor Propane Heater 2026: 5 Portable Propane Heaters Rated for Indoor Use
The best indoor propane heater for most homes is the Mr. Heater Portable Buddy (MH9BX). If you need to warm a whole room, get the Big Buddy (MH18B). Mr. Heater rates both portable propane heaters for emergency indoor use, and both have low-oxygen and tip-over shut-offs. "Indoor-rated" still doesn't mean risk-free. Every manual here requires a fresh-air opening of 4 to 18 sq in and says never run the heater while sleeping, and CPSC and CDC tell you to install battery CO alarms. Below are BTU, runtime per tank, vent size and room limits for each heater, taken from its manual.
As an Amazon Associate, SolarGenAdvisor earns from qualifying purchases made through links on this page, at no additional cost to you. Scores are AI-synthesized from Mr. Heater manuals, spec sheets, Amazon listing details and logged Amazon prices; we did not test these heaters.
By Quick Verdict
For a power outage at home, the Big Buddy heats the most space (about 450 sq ft) and lets you run its low setting in a bedroom while you're awake. The Portable Buddy is the better value for one room and runs about 5.4 hours on a 1 lb cylinder on low. Skip the Buddy FLEX for home use, because its manual bans bedrooms and bathrooms. A propane heater gives you heat while you're awake. For sleeping, use a battery heated blanket, and if you have a gas furnace, use a power station to run its blower (how that works).
Before You Light Any Propane Heater Indoors
- Never while sleeping, never unattended. Every Buddy manual on this page says "NEVER OPERATE THE HEATER WHILE SLEEPING!" and "never leave the heater unattended while burning" (MH9BX manual). CPSC warns that carbon monoxide "can kill a sleeping person in less than two hours" (CPSC).
- Open the vent the manual specifies. These are unvented heaters that burn oxygen from the room. Without enough fresh air, the manual says the heater "may give off excessive CARBON MONOXIDE, an odorless, poisonous gas."
- Install battery CO alarms. CPSC says to put battery-operated or battery-backup CO alarms on each level and outside sleeping areas, and to test them monthly (CPSC, Jan 2026). The heater's low-oxygen shut-off isn't a CO detector. A battery alarm in the same room is the job our best portable carbon monoxide detector picks are for.
- Keep it 3 feet from anything that can burn. That includes beds, curtains, sofas and papers (CPSC; USFA). The manuals' minimum clearances are 30 in above and 24 in in front.
- Keep 20 lb tanks outside. "NEVER bring a refillable propane cylinder indoors" (MH9BX manual). Indoors, use only disposable 1 lb cylinders, and attach or remove them outdoors.
How We Score Indoor Propane Heaters
Our power-station matrix doesn't fit fuel heaters, so these scores use a heater-specific rubric. Each score is AI-synthesized from Mr. Heater owner's manuals and spec sheets, Amazon listing details, and Amazon prices checked on November 6, 2026. We did not test any heater. Every input below is published for all five heaters, so no score is low because of missing data. Weights total 100:
- Heating capacity (25): the maker's rated heating area compared with the largest pick (450 sq ft)
- Indoor safety (25): rated by the maker for US indoor use, with low-oxygen (ODS) and tip-over shut-offs. All five meet all three, so all five score the same here.
- Value (20): the lowest live price here divided by this heater's live price
- Runtime per 1 lb cylinder (15): the maker's figure at the lowest setting, compared with the longest
- Fuel options (15): 1 lb cylinders only, or a 20 lb tank kept outdoors on a Mr. Heater hose, or two 1 lb ports as well
Room restrictions such as the FLEX's bedroom ban aren't in the score. We list them on every card and in the table, because they matter more than a few points. Heater scores aren't comparable with our power-station scores.
The 5 Best Indoor Propane Heaters
All five are Mr. Heater Buddy-series heaters. These were the portable models we could confirm that the manufacturer rates for indoor use, that have a published owner's manual, and that Amazon.com sells new and in stock. We left out listings we couldn't tie to an indoor-rated stock number, and a heater-plus-refill-kit bundle, because these manuals say to use only disposable 1 lb cylinders. Specs come from each heater's manual or Mr. Heater spec sheet (linked) and the Amazon listing.
1. Best for Whole Rooms in an Outage
Mr. Heater Big Buddy MH18B, No Fan (4,000-18,000 BTU)
4,000–18,000 BTU · about 450 sq ft · About 5.5 h low / 1.4 h high per 1 lb (11 h low on two) · vent 18 sq in · Score 80/100
Price: $159.00
The Big Buddy is the heater to buy if you need to keep a living room or a small cabin warm, not just one corner. It has three settings (4,000, 9,000 and 18,000 BTU) and Mr. Heater rates it for up to 450 sq ft. It takes two 1 lb cylinders at once: Mr. Heater's spec sheet gives about 11 hours on low, 4.8 hours on medium and 2.8 hours on high on two cylinders (Mr. Heater spec sheet). For an emergency, its manual sets four conditions: the home's permanent heating is out of service, heat is needed to prevent damage, the heater isn't left unattended, and the room has an 18 sq in fresh-air opening (MH18B manual). This listing is stock number F274805, which Mr. Heater's catalog lists as the Big Buddy without a fan. That makes it quieter and leaves nothing to plug in, but it moves less warm air than the fan version.
Room limits (manual): Bathroom: LO only; bedroom: LO or MED; never while sleeping (manual). Model: MH18B (stock F274805, no fan).
Pros
- ✓ Most heat here: up to 18,000 BTU for about 450 sq ft
- ✓ Two 1 lb ports, or a 20 lb tank kept outdoors via hose
- ✓ Low setting allowed in a bedroom per the manual (never while sleeping)
- ✓ Sold by Amazon.com
Cons
- ✗ Needs the largest vent opening here (18 sq in)
- ✗ No-fan version: less air movement than the fan model
- ✗ Highest price of the five
2. Best Value and Most Versatile
Mr. Heater Portable Buddy MH9BX (4,000-9,000 BTU)
4,000–9,000 BTU · about 225 sq ft · About 5.4 h low / 2.4 h high per 1 lb · vent 9 sq in · Score 75/100
The Portable Buddy is the heater most people mean by "Buddy heater," and it's the one we'd keep for outages in an apartment or a single room. It has two settings, 4,000 and 9,000 BTU, for about 225 sq ft per the current Amazon listing (an older Mr. Heater spec sheet said 200). Amazon's listing gives 5.4 hours on low and 2.4 hours on high from one 1 lb cylinder, while the manual gives a range of 3 to 6 hours. The manual describes it as a heater for "recreational and emergency indoor use" and certifies it to ANSI Z21.103, the standard for unvented portable heaters for indoor and outdoor use. It calls for a 9 sq in fresh-air opening at both ceiling and floor level (MH9BX manual). For a bigger room, step up to the Big Buddy.
Room limits (manual): Bathroom: LO only; bedroom: HI or LO; never while sleeping (manual). Model: MH9BX (stock F232000).
Pros
- ✓ Low-oxygen (ODS) and tip-over shut-offs
- ✓ Long runtime on low: about 5.4 h per 1 lb
- ✓ Bedroom use allowed on HI or LO per the manual (never while sleeping)
- ✓ Sold by Amazon.com; second-lowest price here
Cons
- ✗ Only about 225 sq ft
- ✗ Two heat settings, no thermostat
- ✗ Needs a 9 sq in opening at ceiling and at floor level
3. Best Mid-Size for Cabins and Blinds
Mr. Heater Hunting Buddy MH12HB (6,000-12,000 BTU)
6,000–12,000 BTU · about 300 sq ft · Up to 1.5–3.5 h per 1 lb (high/low) · vent 12 sq in · Score 68/100
Price: $126.00
The Hunting Buddy sits between the Buddy and the Big Buddy, with 6,000 or 12,000 BTU for about 300 sq ft per the Amazon listing. Its manual describes it as a heater for "recreational, commercial and emergency indoor use", certified to CSA 4.98, and lists cabins, enclosed porches and fishing huts as typical enclosures. It needs a 12 sq in fresh-air opening and gives "up to 1.5 to 3.5 hours" per 1 lb cylinder, or 36 to 72 hours on a 20 lb tank kept outdoors (MH12HB manual). That's less runtime per cylinder than the Buddy on low, because its low setting burns 6,000 BTU instead of 4,000. This listing is the camo version (stock F232035).
Room limits (manual): Recreational or commercial enclosure with a window or roof vent; never while sleeping (manual). Model: MH12HB (stock F232035).
Pros
- ✓ 6,000/12,000 BTU for about 300 sq ft
- ✓ ODS and tip-over shut-offs
- ✓ 20 lb tank option via hose (tank outdoors)
- ✓ Sold by Amazon.com
Cons
- ✗ Shorter 1 lb runtime than the Buddy on low
- ✗ Room area figure is from the Amazon listing only
- ✗ Camo styling may not suit a living room
4. Best for Garages and Ice Huts (Not Bedrooms)
Mr. Heater Buddy FLEX MH11BFLEX (8,000-11,000 BTU)
8,000–11,000 BTU · about 275 sq ft · Up to 1.5–3.5 h per 1 lb (high/low) · vent 11 sq in · Score 66/100
Price: $129.00
The Buddy FLEX puts out 8,000 to 11,000 BTU from an omni-directional fiber-mesh burner and is rated for about 275 sq ft (Amazon listing; DICK'S listing). The FLEX is the only heater here whose manual says "DO NOT USE THIS HEATER IN THE BATHROOM OR BEDROOM!" (MH11BFLEX manual). It's also less frugal: its lowest setting is 8,000 BTU, so the manual gives only "up to 1.5 to 3.5 hours" per 1 lb cylinder. It needs an 11 sq in opening at ceiling and floor level. That makes it a good fit for a garage workshop, ice hut or enclosed porch, and a poor fit as a home outage heater.
Room limits (manual): Do NOT use in a bathroom or bedroom; never while sleeping (manual). Model: MH11BFLEX (stock F600100).
Pros
- ✓ 8,000–11,000 BTU for about 275 sq ft
- ✓ ODS and tip-over shut-offs
- ✓ 20 lb tank option via hose (tank outdoors)
- ✓ Sold by Amazon.com
Cons
- ✗ Manual prohibits bedroom and bathroom use
- ✗ Shortest 1 lb runtime on low (8,000 BTU minimum)
- ✗ Wider 24 in side clearance than the other Buddies
5. Best for Very Small Spaces
Mr. Heater Little Buddy MH4B (3,800 BTU)
3,800 BTU · about 95 sq ft · About 5–5.6 h per 1 lb (one setting) · vent 4 sq in · Score 66/100
Price: $76.99
The Little Buddy has a single 3,800 BTU setting for about 95 sq ft and screws directly onto one 1 lb cylinder on an 8 in round stand. Mr. Heater's catalog sheet gives 5.6 hours per cylinder and the manual says about 5 hours (Mr. Heater catalog; MH4B manual). It needs only a 4 sq in fresh-air opening, the smallest here. It's an ice-fishing, hunting-blind or small-office heater. In a power outage it can take the chill off a small room you're sitting in, but it won't warm a living room. Buy this exact listing: stock F215100 is the US indoor version, while Mr. Heater's catalog lists F215120 as the Massachusetts/Canada version.
Room limits (manual): Recreational or commercial enclosure with a window or roof vent; never while sleeping (manual). Model: MH4B (stock F215100).
Pros
- ✓ Lowest price here
- ✓ Long runtime: about 5 to 5.6 h per 1 lb
- ✓ Smallest vent requirement (4 sq in)
- ✓ Sold by Amazon.com
Cons
- ✗ Only about 95 sq ft
- ✗ One heat setting; 1 lb cylinders only
- ✗ Low stock when we checked ("only 1 left")
Indoor Propane Heater Comparison Table
These are the figures as Mr. Heater publishes them in each manual, spec sheet or Amazon listing. Heating area is the maker's rating. A drafty or poorly insulated room needs more heat than the rating assumes.
| Heater | BTU/h | Area | Runtime per 1 lb | Fuel | Vent opening | Room limits (manual) | Score | Price |
|---|---|---|---|---|---|---|---|---|
| Mr. Heater Big Buddy MH18B, No Fan (4,000-18,000 BTU) | 4,000–18,000 | ~450 sq ft | About 5.5 h low / 1.4 h high per 1 lb (11 h low on two) | One or two 1 lb cylinders, or one or two 20 lb tanks outdoors via hose + filter | 18 sq in | Bathroom: LO only; bedroom: LO or MED; never while sleeping (manual) | 80/100 | $159.00 |
| Mr. Heater Portable Buddy MH9BX (4,000-9,000 BTU) | 4,000–9,000 | ~225 sq ft | About 5.4 h low / 2.4 h high per 1 lb | 1 lb cylinder, or 20 lb tank outdoors via Mr. Heater hose + filter | 9 sq in | Bathroom: LO only; bedroom: HI or LO; never while sleeping (manual) | 75/100 | Check price at Amazon → |
| Mr. Heater Hunting Buddy MH12HB (6,000-12,000 BTU) | 6,000–12,000 | ~300 sq ft | Up to 1.5–3.5 h per 1 lb (high/low) | 1 lb cylinder, or 20 lb tank outdoors via hose | 12 sq in | Recreational or commercial enclosure with a window or roof vent; never while sleeping (manual) | 68/100 | $126.00 |
| Mr. Heater Buddy FLEX MH11BFLEX (8,000-11,000 BTU) | 8,000–11,000 | ~275 sq ft | Up to 1.5–3.5 h per 1 lb (high/low) | 1 lb cylinder, or 20 lb tank outdoors via hose | 11 sq in | Do NOT use in a bathroom or bedroom; never while sleeping (manual) | 66/100 | $129.00 |
| Mr. Heater Little Buddy MH4B (3,800 BTU) | 3,800 | ~95 sq ft | About 5–5.6 h per 1 lb (one setting) | One 1 lb cylinder only | 4 sq in | Recreational or commercial enclosure with a window or roof vent; never while sleeping (manual) | 66/100 | $76.99 |
All five have a low-oxygen (ODS) shut-off and a tip-over shut-off per their manuals and listings. Every manual says the heater is "for US sale except Massachusetts" and is "not for use in a 'dwelling home' in California." Certification: Buddy and Big Buddy manuals cite ANSI Z21.103-2017; Little Buddy and Hunting Buddy manuals cite CSA 4.98. All five manuals warn that runtimes can drop sharply when the heater runs continuously below 20°F, and the Buddy, Big Buddy, Little Buddy and Hunting Buddy manuals say the heater may shut off above 7,000 ft.
Is It Safe to Use a Propane Heater Indoors?
Only if the manufacturer rates that heater for indoor use, and only when you follow its manual. All five heaters here are unvented. They burn propane in the room and release the combustion gases into it, and each manual warns that "it uses air (oxygen) from the area in which it is used. Adequate combustion and ventilation air must be provided" (MH9BX manual). In its space-heater safety guidance, CPSC says unvented heaters burning natural gas, LP and other fuels "pose the greatest threat" among space heaters, need "a constant supply of fresh air", and have been outlawed in some areas (CPSC).
The stakes are high. CDC says more than 400 Americans die each year from unintentional carbon monoxide poisoning not linked to fires, more than 100,000 visit an emergency department and more than 14,000 are hospitalized (CDC). Heating fires are a separate risk. USFA estimates 32,200 home heating fires in 2021 caused 190 deaths, and portable heaters were involved in only 3% of home heating fires in 2017–2019 but 41% of the fatal ones (USFA).
What the low-oxygen shut-off (ODS) does, and doesn't do
The Buddy, Big Buddy and FLEX manuals describe a safety system "designed to turn off the heater if not enough fresh air is available," and the Little Buddy and Hunting Buddy list an oxygen depletion sensor (ODS). That shut-off is triggered by low oxygen. It doesn't measure carbon monoxide, and it doesn't replace the vent opening the same manual requires. If the heater keeps shutting off, the manual says not to relight it until you provide fresh air, and to have it serviced if it keeps happening. Early CO symptoms "resemble the flu, with headache, dizziness, and/or nausea"; the manual's instruction is "Get fresh air at once!" CDC says to put battery-operated or battery-backup CO detectors near every sleeping area and replace them as the maker directs or every 5 years (CDC). CPSC adds that interconnected alarms are best, because when one sounds they all sound (CPSC CO center).
Can you use a propane heater in a bedroom?
The Buddy and Big Buddy manuals follow a rule for emergency home use: no more than 5,000 BTU/h in a bathroom and no more than 10,000 BTU/h in a bedroom. That's why the Big Buddy is limited to LO or MED in a bedroom and LO only in a bathroom. The FLEX manual bans both rooms outright. Every manual also says never to run the heater while you're asleep, so "bedroom use" means warming the room while you're awake. Turn it off before bed (MH18B manual; USFA).
Indoor-Rated vs Outdoor-Only Propane Heaters
"Propane heater" covers very different products, and a list of "indoor propane heaters" often mixes in heaters that aren't rated for indoor use. Check the label and manual of the exact model and stock number you're buying:
Indoor-rated (what this page covers)
- ✓ The manual says indoor use. For example, the Buddy's says "recreational and emergency indoor use"
- ✓ It's certified to a standard such as ANSI Z21.103 (unvented portable heaters "for indoor and outdoor use") or CSA 4.98
- ✓ It has a low-oxygen shut-off and a tip-over shut-off
- ✓ It runs on 1 lb disposable cylinders indoors, and any 20 lb tank stays outside
- ✓ It still needs a vent opening and a CO alarm, and must never run while you sleep
Outdoor-only (never bring inside)
- ✗ The label or manual says "for outdoor use only," or says nothing about indoor use
- ✗ Example: Mr. Heater's own tank-top heater (MH12T) is labeled for outdoor use only. Its manual warns that any combustion "will produce carbon monoxide" and says not to use it to heat human living quarters (MH12T manual)
- ✗ Regional versions of the same heater can differ. Mr. Heater's Big Buddy catalog sheet says it is outdoor-only in Massachusetts and Canada (catalog), and the Buddy spec sheet says outdoor use only in Canada (spec sheet)
- ✗ Using an indoor-rated heater outside its manual: the manuals prohibit third-party accessories and attachments and cooking on the heater, and they specify disposable 1 lb cylinders
State restrictions we could verify
Massachusetts: every Buddy manual here is marked "for US sale except Massachusetts," and Mr. Heater's catalog says the Massachusetts/Canada versions are certified for outdoor use only there. California: the same manuals carry the notice "Not for use in a 'dwelling home' in California." Mr. Heater's documents don't explain why, and we couldn't find a state source to add, so we're reporting only what the manufacturer says. Local fire codes can be stricter. CPSC notes that unvented heaters have been outlawed in some areas, so check with your local fire department.
How Long Does a 1 lb Propane Tank Last in a Buddy Heater?
Roughly 21,600 BTU per pound of propane ÷ the heater's BTU setting. We worked that number out from Mr. Heater's own Buddy figures: 9,000 BTU × 2.4 h and 4,000 BTU × 5.4 h both equal 21,600 BTU per 1 lb cylinder. It also matches the Big Buddy's figure of up to 216 hours on two 20 lb tanks on low (864,000 BTU ÷ 4,000). EIA puts propane at 91,452 Btu per gallon (EIA). These are estimates for full cylinders at mild temperatures. Every manual warns that runtimes "can be significantly reduced" when the heater runs continuously below 20°F.
| Setting (BTU/h) | Which heater | One 1 lb cylinder | Two 1 lb cylinders | One 20 lb tank (outdoors, via hose) |
|---|---|---|---|---|
| 3,800 | Little Buddy | ~5.7 h | ~11 h | n/a (1 lb only) |
| 4,000 | Buddy / Big Buddy low | ~5.4 h | ~11 h | ~108 h |
| 6,000 | Hunting Buddy low | ~3.6 h | ~7.2 h | ~72 h |
| 8,000 | Buddy FLEX low | ~2.7 h | ~5.4 h | ~54 h |
| 9,000 | Buddy high / Big Buddy medium | ~2.4 h | ~4.8 h | ~48 h |
| 12,000 | Hunting Buddy high | ~1.8 h | ~3.6 h | ~36 h |
| 18,000 | Big Buddy high | ~1.2 h | ~2.4 h | ~24 h |
These are our estimates, not measurements. Manufacturer figures vary by document: the FLEX and Hunting Buddy manuals say "up to 1.5 to 3.5 hours" per 1 lb cylinder, and the MH9BX manual gives "3 to 6 hours" per 1 lb and "48 to 110 hours" on 20 lb. Only the Big Buddy (two ports) can run two 1 lb cylinders at once. For emergency heat inside a home, the Buddy manuals specify disposable 1 lb cylinders, and a 20 lb tank on a hose must stay outdoors.
What that means in an outage: a 3-day outage with the Portable Buddy on low for 8 hours a day uses about 24 hours of burn time, or roughly five 1 lb cylinders. Store spare cylinders outdoors, as the manuals require, and don't bring them in until you need them.
Do Indoor Propane Heaters Need Ventilation?
Yes. Every manual sets a minimum fresh-air opening, and the bigger the heater, the bigger the opening. A window cracked open to the area listed below is the simplest way to meet it. The Buddy and FLEX manuals specify the opening "at the ceiling and at floor level." All of them say not to use other fuel-burning appliances in the same space.
| Heater | Minimum vent area | Manual's example | Clearance (top / front / sides) |
|---|---|---|---|
| Little Buddy MH4B | 4 sq in | 2 in × 2 in | 30 / 24 / 6 in |
| Portable Buddy MH9BX | 9 sq in, at ceiling and floor | 3 in × 3 in | 30 / 24 / 6 in |
| Buddy FLEX MH11BFLEX | 11 sq in, at ceiling and floor | 5.5 in × 2 in | 30 / 24 / 24 in |
| Hunting Buddy MH12HB | 12 sq in | 3 in × 4 in | 30 / 24 / 6 in |
| Big Buddy MH18B | 18 sq in | 4.25 in × 4.25 in | 30 / 24 / 6 in |
Source: each heater's owner's manual (linked on its card above). Rear clearance is 0 in for all five. CPSC's general rule for portable heaters is at least 3 feet from beds, clothes, curtains, papers and sofas, which is wider than the manuals' front clearance, so use 3 feet (CPSC).
Propane Heater for a Power Outage: Where It Fits
A propane heater makes heat without electricity, which is why it outlasts any battery when you're heating a room. For comparison, 1 watt equals 3.412 BTU/h (EIA), so a 1,500W electric space heater puts out about 5,100 BTU/h. Here's how long each heat source lasts:
| Heat source | Heat output | How long it lasts | While sleeping? |
|---|---|---|---|
| Portable Buddy on low, one 1 lb cylinder | 4,000 BTU/h (≈1,170W of heat) | ~5.4 h (Mr. Heater) | No (manual) |
| 1,500W space heater on a Jackery Explorer 1000 V2 (1,024 Wh) | ≈5,100 BTU/h | ~0.6 h | No (USFA: turn heaters off at bedtime) |
| 50W 12V heated blanket on the same station | Warms the person, not the room | ~17 h | Follow the blanket's manual |
Power-station runtimes are continuous-draw estimates (Wh × 0.85 ÷ W), not measurements. Battery-heater math is in our battery powered heater guide and space heater runtime guide.
The plan that works for most homes has three layers. First, if you have a gas or propane furnace, power its blower and controls from a power station. That brings back whole-home heat for a few hundred watts (can a power station run a furnace?). Second, use an indoor-rated propane heater for supervised daytime warmth in the room you're in, with the window cracked and a CO alarm on. Third, at bedtime turn the heater off and switch to battery or 12V heated blankets, which make no fumes. Never run a generator, grill or camp stove indoors for heat (CDC). A battery power station is the only indoor-safe "generator".
Furnace blower + blankets: Jackery Explorer 1000 V2
1,024 Wh and 1,500W AC, with a score of 93/100 in our power-station scoring. It runs a 50W 12V blanket for about ~17 h. How long it can run a furnace blower depends on the blower's draw, which our furnace guide covers. Currently $559.00 on Amazon. Full review.
Alternative: EcoFlow Delta 3 Plus
1,024 Wh and 1,800W AC, with a score of 89/100 in our power-station scoring. Its capacity is close to the Jackery's, so blanket runtimes are similar (about ~17 h at 50W). Currently $719.00 on Amazon. Full review.
Planning for a multi-day storm? Our winter storm power backup guide sizes a station for heat, the fridge and phones together. Running a propane generator as well? Our best propane generator guide covers the outdoor-only rules for those. Weighing kerosene vs propane? A gallon of kerosene holds about as much heat as six 1 lb cylinders, but kerosene wick heaters have no low-oxygen shut-off; our best kerosene heater guide compares the two.
Big Buddy vs Buddy vs Buddy FLEX: Which Mr. Heater Buddy?
- Buddy (MH9BX): one room up to about 225 sq ft, with the longest runtime per cylinder on low among the multi-setting Buddies. Best for apartments and single-room outage heat.
- Big Buddy (MH18B): about twice the area (450 sq ft) and a third setting. It holds two 1 lb cylinders, so you swap cylinders half as often for the same burn time. This listing (stock F274805) has no fan. Mr. Heater's catalog lists fan versions under other stock numbers (F274800, plus F274865 for Massachusetts/Canada), so check the stock number on the box if you want one (Mr. Heater catalog). Currently $159.00 on Amazon.
- Buddy FLEX (MH11BFLEX): more heat than the Buddy, but a higher minimum setting (8,000 BTU) and a manual that bans bedroom and bathroom use. It's a garage, porch or ice-hut heater rather than a home outage heater. For a workshop or ice hut where you can pipe exhaust outdoors, a vented portable diesel heater is the other option.
Indoor Propane Heater Buying Guide
- Confirm the indoor rating on the exact stock number. The same model name can be sold as a US indoor version or a Massachusetts/Canada outdoor-only version. The Little Buddy, for example, is F215100 (US) or F215120 (MA/Canada) in Mr. Heater's catalog.
- Size by room, not by the biggest BTU number. Pick the smallest heater whose rated area covers the one room you'll close off. Small heaters need smaller vent openings, use less fuel and stay within the manuals' bedroom (10,000 BTU) and bathroom (5,000 BTU) limits.
- Check the room rules in the manual. The FLEX manual bans bedrooms and bathrooms, and the Big Buddy is limited to LO/MED in a bedroom. All of them are prohibited while you sleep.
- Plan the fuel. Indoors, use 1 lb disposable cylinders. A 20 lb tank must stay outside on a Mr. Heater hose and fuel filter. The manuals prohibit third-party accessories and attachments.
- Know the limits. The manuals warn that runtimes drop sharply below 20°F, and most say the heater may shut off above 7,000 ft. In California, the manuals say these heaters are not for use in a dwelling home.
- Budget for a CO alarm. Battery or battery-backup CO alarms on each level and outside sleeping areas, tested monthly (CPSC). Without one, don't use any fuel-burning heater indoors.
Every price on this page loads live from Amazon. Stock on smaller models like the Little Buddy was already low when we checked, and we can't predict prices or promise a discount on any listing.
Who Should Buy an Indoor Propane Heater (and Who Should Skip)
Good fit
- ✓ Homes that lose power in winter and need daytime room heat without electricity
- ✓ Cabins, enclosed porches, workshops and ice huts with a window or roof vent
- ✓ People who will crack a window, run a CO alarm and stay with the heater
- ✓ Households pairing it with a power station for the furnace blower and blankets
Skip it if
- ✗ You want heat while you sleep (use heated blankets on a power station instead)
- ✗ You can't provide the manual's vent opening, or don't have a working CO alarm
- ✗ You live in Massachusetts, or want a heater for a dwelling home in California (per the manuals)
- ✗ Small children or pets can't be kept away from a hot radiant face
Indoor Propane Heater FAQ
Is it safe to use a propane heater indoors?
Only if the manufacturer rates that exact heater for indoor use, and only if you follow its manual. All the indoor-rated heaters on this page are unvented. They need the fresh-air opening their manual specifies (4 to 18 sq in), at least 3 feet of clearance from anything that can burn, and someone awake nearby. Mr. Heater's manuals say never to run them while sleeping. CPSC and CDC say to install battery or battery-backup carbon monoxide alarms, because the heater's low-oxygen shut-off is not a CO detector.
What is the best indoor propane heater?
In our scoring the Mr. Heater Big Buddy (MH18B) ranks highest. It has three settings up to 18,000 BTU for about 450 sq ft and takes two 1 lb cylinders. The Portable Buddy (MH9BX) is the better value for one room, with 4,000 or 9,000 BTU for about 225 sq ft and about 5.4 hours per 1 lb cylinder on low. The Little Buddy suits very small spaces of about 95 sq ft.
Is the Mr. Heater Buddy safe to use indoors?
Mr. Heater rates the Portable Buddy (MH9BX) for recreational and emergency indoor use in the US, certified to ANSI Z21.103, with low-oxygen and tip-over shut-offs. Its manual requires a 9 sq in fresh-air opening at ceiling and floor level, says never to operate it while sleeping or leave it unattended, and says to use only disposable 1 lb cylinders indoors. It is not sold for use in Massachusetts, and the manual says it is not for use in a dwelling home in California.
How long does a 1 lb propane tank last in a Buddy heater?
Mr. Heater lists about 5.4 hours on low (4,000 BTU) and 2.4 hours on high (9,000 BTU) for the Portable Buddy. A quick rule is about 21,600 BTU per pound divided by the BTU setting. The Buddy FLEX and Hunting Buddy last up to about 3.5 hours per cylinder on low, and the Little Buddy about 5 to 5.6 hours. Runtimes drop sharply when the heater runs continuously below 20 degrees F.
Can I sleep with a propane heater on?
No. Every Mr. Heater Buddy manual on this page says never to operate the heater while sleeping, and USFA says to turn space heaters off when going to bed. CPSC warns that carbon monoxide can kill a sleeping person in less than two hours. For warmth at night during an outage, use a heated blanket on a power station and keep a CO alarm outside sleeping areas.
Do indoor propane heaters need ventilation?
Yes. Each manual sets a minimum fresh-air opening: 4 sq in for the Little Buddy, 9 sq in for the Portable Buddy, 11 sq in for the Buddy FLEX, 12 sq in for the Hunting Buddy and 18 sq in for the Big Buddy. The Buddy and FLEX manuals specify the opening at both ceiling and floor level. Without enough fresh air, the manuals warn the heater may give off excessive carbon monoxide.
Big Buddy vs Buddy: which should I buy?
Buy the Portable Buddy for one room up to about 225 sq ft and the longest runtime per cylinder on low. Buy the Big Buddy for a larger room or cabin up to about 450 sq ft: it adds an 18,000 BTU high setting and a second 1 lb cylinder port, but needs an 18 sq in vent opening instead of 9. The Big Buddy listing on this page is the no-fan version.
Is a propane heater or a battery heater better for a power outage?
For room heat, propane lasts far longer. One 1 lb cylinder runs a Buddy on low for about 5.4 hours, while a 1,500W electric heater empties a 1,024 Wh power station in about 35 minutes. For sleeping, a battery wins: a 50W heated blanket runs about 17 hours on the same station and makes no fumes. Many households use both, plus a power station to run a gas furnace's blower.