How Long Does a Buddy Heater Last? 1 lb vs 20 lb
How long does a Buddy heater last? Run times for Little Buddy, Buddy and Big Buddy on 1 lb and 20 lb tanks, with cost per night and cold-weather math.
The first cold night of the season, the heater is the whole plan. You set the Buddy on the tent floor, crack the vent, and settle in — and then somebody asks the question that decides whether tomorrow night is warm too: how long does a Buddy heater last on the tank we brought?
The answer is arithmetic, not luck. Every Mr. Heater Buddy model burns propane at a published rate, and every propane container holds a known number of BTUs. Divide one by the other and you know exactly where you stand before you ever light it. What follows is the run time for each model on each tank size, the cost per night of the cheap way and the expensive way, and the reasons your real-world number usually comes in under the chart.
How Long Does a Buddy Heater Last? The Short Answer
A Buddy heater on a 1 lb cylinder lasts about 2.4 hours on high and 5.4 hours on low. On a 20 lb tank the same heater runs roughly 48 hours on high or 108 hours on low. The Little Buddy stretches a 1 lb cylinder to about 5.6 hours; the Big Buddy can run 24 hours on high from a 20 lb tank.
That is the whole headline. Everything below is the same math applied to each model, each setting, and the weather you will actually meet in November.
Mr. Heater Buddy Run Time Chart
| Heater model | Setting (BTU) | 1 lb cylinder | 20 lb tank | 5 lb tank |
|---|---|---|---|---|
| Little Buddy MH4B | 3,800 | 5.6 h | ~110 h | ~28 h |
| Buddy MH9BX | Low (4,000) | 5.4 h | ~108 h | ~27 h |
| Buddy MH9BX | High (9,000) | 2.4 h | ~48 h | ~12 h |
| Big Buddy MH18B | Low (4,000) | 5.4 h | ~108 h | ~27 h |
| Big Buddy MH18B | Medium (9,000) | 2.4 h | ~48 h | ~12 h |
| Big Buddy MH18B | High (18,000) | 1.2 h | ~24 h | ~6 h |
Two things worth knowing about that table. The Big Buddy draws from two 1 lb cylinders at once, so its 1 lb numbers double in practice — 10.8 hours on low, 4.8 on medium, 2.4 on high with a matched pair. And the 5 lb column is the sleeper deal for weekend trips: light enough to carry, cheap to refill, still measured in days rather than hours.
The Buddy itself is the model most people mean. It is a 4,000/9,000 BTU radiant unit with a tip-over switch and an oxygen depletion sensor, and at $74 it is the cheapest way into the Buddy family: Mr. Heater MH9BX Buddy heater. If you only ever heat one small tent on weekend trips, this is the one to buy.
How Long Does a Buddy Heater Last on a 1 lb Tank?
Five hours on low, two and a half on high — and a whole weekend plan riding on those numbers.
The math: a 16.4 oz (1 lb) propane cylinder holds 21,600 BTU. The Buddy burns 4,000 BTU per hour on low, so 21,600 ÷ 4,000 = 5.4 hours. On high it burns 9,000 per hour, so 21,600 ÷ 9,000 = 2.4 hours. That is it. No efficiency mystery, no break-in period — the only variables are ambient temperature and how full the cylinder really is.
In practice, one cylinder gets you one chilly evening: dinner, dishes, the hour before bed. A full eight-hour night at 4,000 BTU needs 32,000 BTU, or about 1.5 cylinders — so bring two per night if you plan to leave it running, three if it will be below freezing.
Buy them by the dozen or pay tourist prices at the camp store. The Coleman 16.4 oz propane cylinder 12-pack at $64.99 works out to about $5.42 a cylinder, which is the realistic baseline for the cost comparison further down.
One cold-weather caveat that catches first-timers: a 1 lb steel cylinder chills fast as it vaporizes. At 20°F the tank surface ices, pressure drops, and the flame gets shorter before the cylinder is empty. Sitting the cylinder in a shallow pan of cool water — never hot, never near a flame — buys back some of that.
How Long Does a Buddy Heater Last on a 20 lb Tank?
About 48 hours on high, 108 hours on low, and effectively a whole season of weekend trips.
A 20 lb tank holds roughly 430,000 BTU (4.6 gallons at about 91,500 BTU per gallon). Divide by 9,000 BTU per hour and you get 47.8 hours on high; divide by 4,000 and you get 107 hours on low. Run the Buddy off a bulk tank and the heater stops being the thing you ration.
To do it you need two small parts and one habit:
- A hose, because the tank does not sit on the heater. The Mr. Heater 10-foot Buddy series hose assembly screws into the Buddy's 1"-20 throwaway-cylinder thread and ends in a QCC1 fitting for the tank.
- A filter, because bulk tanks carry compressor oil and rust that a 1 lb cylinder does not. The Mr. Heater universal propane fuel filter for Buddy heaters is a $16 part that protects a $74 heater; Mr. Heater requires it on hose setups, and skipping it is the most common cause of a clogged orifice that never quite lights right again.
- The habit: close the tank valve and burn the hose line empty before you pack up, so the hose does not sit pressurized all week.
A 20 lb tank also changes the cold-weather story. Where a 1 lb cylinder frosts in an hour, a 20 lb tank keeps vaporizing through single digits — set it on a scrap of foam or a board rather than directly on frozen ground, and never in a closed vehicle. If you want the full run-time math on the tank itself, our 20 lb propane tank run-time guide carries the appliance-by-appliance table, and the 1 lb canister guide does the same for throwaway cylinders and stove burners.
Little Buddy Heater Run Time: About 5.6 Hours on a 1 lb Cylinder
The Little Buddy MH4B is the 3,800 BTU personal unit — the one that lives in an ice fishing shelter, a hunting blind, or the footwell of a small tent. Mr. Heater rates it at 5.6 hours on a 1 lb cylinder, and the math agrees: 21,600 ÷ 3,800 = 5.7 hours.
People phrase this search a dozen different ways — how long will little buddy heater run, how long does little buddy heater last on low, how long will a little buddy heater run on a 1lb tank — and the answer does not change with the phrasing. It is one setting, one burn rate, one number. Cold weather is the only thing that moves it, and it moves it down: expect 4.5 to 5 hours when the cylinder is frosting.
At $69.99 the Mr. Heater Little Buddy 3,800 BTU heater is the right buy for one or two people in a small space, and the wrong buy for a four-person cabin tent — it simply does not have the output to move that much cold air.
Big Buddy Heater: Two 1 lb Cylinders or a 20 lb Tank
The Mr. Heater Big Buddy MH18B is the 4,000 / 9,000 / 18,000 BTU triple-rate unit, and the one people underestimate. On high it drinks 18,000 BTU per hour, so a single 1 lb cylinder is gone in 72 minutes. With the two-cylinder manifold it comes with, that becomes 2.4 hours on high, 4.8 on medium, and 10.8 on low.
On a 20 lb tank the Big Buddy runs about 24 hours on high, 48 on medium, and 108 on low. If you are heating a large tent or a wall tent with an annex, that is the honest number to budget: one tank, one weekend, high setting, done.
Buddy Heater Propane Usage: Ounces Per Hour
If you would rather think in fuel than in hours, this is the conversion. Propane delivers about 1,350 BTU per ounce, which makes every Buddy setting a fixed fuel draw:
- Little Buddy, 3,800 BTU: 2.8 oz per hour
- Buddy or Big Buddy, low, 4,000 BTU: 3.0 oz per hour
- Buddy or Big Buddy, medium, 9,000 BTU: 6.7 oz per hour
- Big Buddy, high, 18,000 BTU: 13.3 oz per hour
A 1 lb cylinder is 16.4 oz, which is why the Little Buddy's 5.6 hours and the Buddy's 5.4 come out so close — the two burn rates differ by only 200 BTU. And it is why "buddy heater propane usage" is really a question about the setting, not the heater: dropping from high to low more than halves your fuel bill for the same evening.
What a Night Actually Costs: 1 lb vs 20 lb
This is where the two tank sizes stop being interchangeable.
On 1 lb cylinders, at $5.42 each, propane costs about $0.33 per ounce. A Buddy on high burns $2.21 an hour; on low, $0.98 an hour. Eight hours on low is roughly $7.85 of propane, and you will be swapping cylinders in the dark at least once.
On a 20 lb refill, at a typical $20 for 20 lb (320 oz), propane costs about $0.0625 per ounce — a little over five times cheaper. The same eight hours on low costs about $1.50, and the tank does not need changing.
Two ways to close that gap without carrying a bulk tank:
- The Flame King refillable 1 lb cylinder with refill kit lets you top your own DOT cylinders from a 20 lb tank at home. It pays for itself in about a dozen refills.
- The Gas One 1 lb to 20 lb refill adapter with 4-foot hose does the transfer itself, so the 20 lb tank stays in the garage and only the small cylinders travel.
The full cost comparison — including how many trips it takes to justify each option — is in our 1 lb vs 20 lb cost per trip breakdown, and the safe refill procedure is in how to refill 1 lb propane bottles safely. Refilling is legal for DOT cylinders and safe when you weigh the cylinder; it is not safe when you guess.
Why Your Heater Quits Before the Chart Says
Every winter someone reports a Buddy that "only lasted an hour." Ninety percent of the time it is one of these six:
- It is on high. The chart's 5.4 hours is the low setting. High is 2.4 — and most people light it on high and never turn it down.
- The cylinder is cold. Below about 20°F, vaporization slows and the flame shrinks while the cylinder still has fuel in it. Warm the cylinder slowly in cool water, never with a flame or a heater.
- The tank is not as full as you think. Exchange tanks are often filled to 15 lb, not 20 — a full exchange cylinder weighs 32-33 lb instead of the 37-38 lb of a true fill. More on catching that below.
- The filter or orifice is clogged. Bulk-tank oil and rust accumulate in the orifice; the heater lights, runs weak, and shuts off. This is exactly what the fuel filter prevents.
- It is windy. Radiant heat blows away, so the tent never reaches temperature and the heater runs longer than the chart assumes. A wind break changes the number more than a bigger heater does.
- The ODS is doing its job. The oxygen depletion sensor shuts the unit off in a space with poor ventilation — or at high altitude, where the pilot flame reads "wrong" to the sensor. Above roughly 7,000 feet, expect nuisance shutdowns.
If the heater lights and then dies the moment you release the button, that is a different failure and it has its own fix list: Mr. Heater won't stay lit after releasing the button walks the thermocouple, pilot, and ODS checks in order.
How to Tell How Much Propane Is Left
You cannot see the level in a steel tank, but you can weigh it or read it:
- Weigh it. A 20 lb tank's tare weight is stamped on the collar (usually 17-18 lb). Full is 37-38 lb. Every pound above tare is a pound of propane, so 25 lb on the scale means you have 7-8 lb left — about 20 hours on low.
- Catch a short exchange fill. An exchange tank reading 32-33 lb was filled to 15 lb, not 20. A $10 bathroom scale in the truck pays for itself once.
- Read it in-line. A propane tank gauge level indicator between the valve and the hose gives you a pressure-based read at a glance. Pressure falls with temperature, so treat it as a trend, not a fuel gauge.
- Use the frost line. Running the heater draws vapor off the top of the liquid; the tank sweats and frosts in a band right at the liquid level. On a cold evening, that line is your fuel gauge.
Overnight in a Tent: The Safety Half of the Run-Time Question
A run-time chart answers "how long will it burn," not "should it burn all night." Those are different questions, and the second one matters more.
Buddy heaters are indoor-rated units with an oxygen depletion sensor, but Mr. Heater's own instructions require ventilation, and no combustion heater belongs in a sealed tent with sleeping people. Carbon monoxide is colorless and the symptoms — headache, drowsiness — read exactly like being tired at the end of a cold day. If you run a heater while you are awake, crack two vents, keep it off the sleeping bags and away from the tent wall, and put a battery-powered Kidde CO detector in the tent before the first cold night. A combustible gas leak detector is the other half of that kit for hose connections.
The pattern that works: heat the tent for the hour before bed and the hour after waking, then shut the heater off and let the sleep system carry the night. Our tent heater safety guide covers BTU-per-tent-size sizing, ventilation, and the hot-tent alternative in detail, and the winter camping gear checklist covers the sleeping-side fix that makes overnight heating unnecessary.
Buddy Heater Run Time: The Answer Key
People arrive here from a dozen different phrasings of the same question, so rather than make you hunt through the prose, here is the lookup table. Find your model or your tank, read the hours.
Buddy and "Mr. Buddy" (4,000 / 9,000 BTU), one 1 lb cylinder or a 20 lb tank:
| Question as people type it | Answer |
|---|---|
| how long does a buddy heater last on low | 5.4 hours on 1 lb; about 108 hours on a 20 lb tank |
| how long does a buddy heater last on high | 2.4 hours on 1 lb; about 48 hours on a 20 lb tank |
| how long does a buddy heater last on a 1 pound tank | 5.4 hours on low, 2.4 hours on high |
| how long does a mr buddy heater last | Same unit, same math: 5.4 h low, 2.4 h high |
| how long does a mr buddy heater last on low | 5.4 hours per 1 lb cylinder |
| how long does a mr buddy propane heater last | 2.4 to 5.4 hours per 1 lb cylinder |
| how long does a mr heater portable buddy last | 5.4 h on low, 2.4 h on high, per 1 lb cylinder |
| mr heater buddy run time | 2.4-5.4 h on 1 lb; 48-108 h on a 20 lb tank |
| mr heater buddy run time on low | 5.4 hours (1 lb) or about 108 hours (20 lb) |
| mr heater portable buddy run time | 48 h on high, 108 h on low, from a 20 lb tank |
| mr heater buddy propane heater run time | High 2.4 h, low 5.4 h per 1 lb cylinder |
| mr buddy heater 9000 btu run time | 2.4 hours on 1 lb; about 48 hours on 20 lb |
| how long does a mr heater last | 2.4-5.4 h per 1 lb; 48-108 h per 20 lb tank |
| how long does a mr heater propane last | Hours = tank BTU divided by the burn rate |
| buddy heater how long does it last | 5.4 hours on low, 2.4 on high, per 1 lb cylinder |
| mr buddy heater how long does it last | 5.4 hours on low, 2.4 on high |
| mr buddy heater how long does propane last | 2.4 h on high, 5.4 h on low per cylinder |
| buddy heater propane usage | 3.0 oz per hour on low, 6.7 oz per hour on high |
Little Buddy (3,800 BTU) and Big Buddy (4,000 / 9,000 / 18,000 BTU):
| Question as people type it | Answer |
|---|---|
| how long does a little buddy heater last | 5.6 hours per 1 lb cylinder |
| how long does a little buddy heater last on low | 5.6 hours — the Little Buddy only has one setting |
| how long does little buddy heater last on low | 5.6 hours, or 4.5-5 hours once the cylinder frosts |
| little buddy heater how long does it last | 5.6 hours on one 1 lb cylinder |
| how long will little buddy heater run | 5.6 hours per cylinder, single setting |
| how long will little buddy heater run on low | 5.6 hours — low is the only setting it has |
| how long will little buddy heater run on a 1lb tank | 5-6 hours, less below 20°F |
| how long will a little buddy heater run on a 1lb tank | 5.6 hours rated, 4.5-5 in the cold |
| mr heater little buddy how long does it last | 5.6 hours |
| mr heater little buddy run time | 5.6 hours on a 1 lb cylinder |
| how long does a big buddy heater last | 10.8 h low, 4.8 medium, 2.4 high on two 1 lb cylinders |
| how long does a big buddy heater last on a 20 lb tank | 108 h low, 48 h medium, 24 h high |
| mr heater big buddy run time | 24-108 hours on a 20 lb tank, by setting |
| mr heater big buddy run time chart | 24 h high, 48 h medium, 108 h low |
| mr heater big buddy 20lb tank run time | 24 h high, 48 h medium, 108 h low |
| mr buddy heater run time on 20 lb tank | 24-108 hours depending on model and setting |
Tank and accessory questions:
| Question as people type it | Answer |
|---|---|
| buddy heater on 20 lb tank | Run the hose to the tank; expect 48 h high, 108 h low |
| how long does a buddy heater last on a 20 lb tank | 48 hours on high, about 108 hours on low |
| buddy heater last on 20 lb tank | 48-108 hours by setting |
| buddy heater run time on 20 lb tank | 48 h on high, 108 h on low |
| mr heater on 20 lb tank | 48 h high, 108 h low on a Buddy |
| little buddy heater on 20 lb tank | About 110 hours |
| big buddy heater on 20 lb tank | 24 h high, 48 h medium, 108 h low |
| mr buddy heater on 20 lb tank | 24-108 hours by model and setting |
| buddy heater 20 lb tank hose | You need a QCC1 hose assembly, 10 ft is the common length |
| buddy heater 20 lb tank adapter | No adapter — the hose ends in the QCC1 nut the tank wants |
| mr heater buddy 20 lb tank adapter | The hose replaces the 1 lb fitting entirely |
| how long does a 1 pound propane tank last in a buddy heater | 5.4 hours on low, 2.4 hours on high |
| how long will a buddy heater run on a 1 lb tank | 5.4 hours on low, 2.4 hours on high |
| mr heater 1 lb tank | 16.4 oz, 21,600 BTU, 2.4-5.4 hours in a Buddy |
| mr heater 1 lb propane tank | Same cylinder: 16.4 oz and 21,600 BTU |
| mr heater 1 lb propane tank run time | 2.4 h on high, 5.4 h on low |
| mr heater 1 lb propane tank refill kit | Flame King refillable cylinder or a Gas One adapter |
| mr heater refillable 1 lb tanks | DOT-compliant refillables, refilled from a 20 lb donor |
| mr heater dual 1 lb tank hook up kit | The Big Buddy's two-cylinder manifold, or a tee hose |
"How much propane does it use?" phrasing:
| Question as people type it | Answer |
|---|---|
| buddy heater propane usage chart | 2.8 to 13.3 oz per hour, by model and setting |
| buddy heater propane use | 3.0 oz/h on low, 6.7 oz/h medium, 13.3 oz/h high |
| buddy heater propane consumption | 1 lb of propane per 2.4-5.4 hours of run time |
| big buddy heater propane usage | 13.3 oz per hour at the 18,000 BTU high setting |
| mr buddy heater propane usage | 3.0-6.7 oz per hour at 4,000-9,000 BTU |
| little buddy heater propane usage | 2.8 oz per hour at 3,800 BTU |
| mr heater propane usage | 3.0 oz/h low, 6.7 oz/h medium, 13.3 oz/h high |
| mr heater propane use | BTU per hour divided by 1,350 BTU per ounce |
| mr heater propane consumption | 2.8-13.3 oz per hour depending on the setting |
| mr heater how long does propane last | Hours = the tank's BTU divided by the burn rate |
| portable buddy heater how long does it last | 5.4 hours on low, 2.4 on high, per 1 lb cylinder |
How Cold Weather Changes the Number
Everything above assumes a tank at room temperature. In the field, the tank is the variable — and it is always the reason a heater "didn't last as long as it should."
Propane has to boil inside the cylinder before it can burn, and cold slows that boil. A 1 lb cylinder has very little liquid surface and very thin walls, so it chills itself as it draws vapor: run a Buddy on high at 25°F and the cylinder frosts within the hour, pressure falls, and the flame shortens while there is still fuel inside. The heater has not become less efficient; the tank has stopped keeping up.
A 20 lb tank behaves much better for the same reason a larger pot of water holds heat longer — more liquid, more surface, more thermal mass. Set it on a piece of foam or a board instead of frozen ground, keep it out of the wind, and it will keep vaporizing into single digits. What you should never do is heat the tank: no torch, no heater aimed at it, no boiling water. A bath of cool water below 110°F is the standard field trick and the only one worth using.
There is one more cold-weather quirk worth knowing. A heater that lights and then dies after five or ten minutes — rather than the instant you release the button — is usually the tank starving the ODS pilot, not a broken thermocouple. That failure has its own diagnostic order in Mr. Heater won't stay lit.
Buddy Heater Run Time FAQ
How long does a Buddy heater last on high?
About 2.4 hours on a 1 lb cylinder and about 48 hours on a 20 lb tank. High is 9,000 BTU per hour, so it burns through a pound of propane in a little over two hours.
How long does a Mr. Heater Buddy last on low?
About 5.4 hours on a 1 lb cylinder and 108 hours on a 20 lb tank. Low is 4,000 BTU per hour, which is the setting the published run times are based on.
How long will a Little Buddy heater run on a 1 lb tank?
5.6 hours at its single 3,800 BTU setting, or roughly 4.5-5 hours in freezing weather once the cylinder starts to frost.
How long does a Big Buddy heater last on a 20 lb tank?
24 hours on high, 48 on medium, and 108 on low. On two 1 lb cylinders it runs 2.4, 4.8, and 10.8 hours respectively.
How many 1 lb cylinders do I need for one night?
Plan on two per night on low and four on high. An eight-hour night at 4,000 BTU needs 32,000 BTU, which is 1.5 cylinders of theoretical fuel — always round up.
Does a Buddy heater work below freezing?
Yes, but output drops. A 1 lb cylinder loses pressure and frosts below about 20°F; a 20 lb tank keeps vaporizing well below zero if it sits on insulation rather than frozen ground.
Can I leave a Buddy heater running all night?
No — not in a sealed tent. Ventilation and a CO alarm are non-negotiable, and the safer pattern is to heat before bed and after waking, then rely on your sleeping bag overnight.
The Bottom Line
How long a Buddy heater lasts is a division problem: 21,600 BTU in a 1 lb cylinder, 430,000 in a 20 lb tank, divided by 4,000, 9,000, or 18,000 BTU per hour depending on the model and the setting. Low and slow, one cylinder covers an evening. A 20 lb tank covers a season.
Buy for the tank you will actually carry. If trips are two nights and the car is nearby, a 20 lb tank with a hose and filter is cheaper within one weekend and never leaves you swapping cylinders in the dark. If you are walking in, ice fishing, or heating a blind, the Little Buddy on 1 lb cylinders is the honest tool — just bring one more cylinder than the chart says.
And whatever you run, put the heater where you can see it, vent the tent, and set the CO alarm before the first cold night. Warm is only worth it if everybody wakes up.
<!-- AFFILIATE_DISCLOSURE -->