How Long Does a 20 lb Propane Tank Last? Burn Time by Appliance (2026)

A 20 lb propane tank is the fuel standard for car camping, tailgating, and any trip where a family cooks more than one meal a day. It is also the tank nobody can estimate: the same cylinder that lasts a whole weekend on a camp stove is gone in an afternoon on a patio heater.

Here is the number, then the math behind it, so you can size a tank to your own appliance instead of someone else's guess.

Quick Answer: How Long Does a 20 lb Propane Tank Last?

A full 20 lb (4.6 gallon) propane tank holds roughly 430,000 BTU of fuel. Divide that by your appliance's burn rate:

• ~43 hours on a 10,000 BTU single-burner camp stove
• ~21 hours with both burners of a 20,000 BTU two-burner stove running full
• ~36 hours on a 12,000 BTU tabletop grill, ~14 hours on a 30,000 BTU gas grill
• ~48 hours on a 9,000 BTU Buddy heater, ~24 hours on an 18,000 BTU Big Buddy
• ~8-9 hours on a 50,000 BTU portable fire pit

For a family that cooks three meals a day on a stove and runs a heater at night, one tank is a long weekend. For someone cooking two meals per day, it is closer to a full season.

What a "20 lb Tank" Actually Holds

The name refers to the weight of the propane, not the tank, and not the water capacity. Three numbers matter:

• 20 lb of propane ≈ 4.6 gallons at propane's 4.24 lb per gallon — the number on the exchange cage and at the refill counter.
• 1 lb of propane ≈ 21,600 BTU of heat, which is why the tank works out to roughly 430,000 BTU total.
• The OPD valve stops filling at 80%, so a "full" 20 lb tank is designed to sit at about 20 lb of fuel — not more. A tank filled past that has no room for expansion on a hot day.

You can verify all of this on the collar. The stamped WC (water capacity) is about 47.6 lb on a standard 20 lb cylinder, and the stamped TW (tare weight) is typically 17-18 lb. A full tank weighs about 37-38 lb. Those two numbers are the whole reason you can check your fuel level with a bathroom scale later in this guide.

What it is not: a 20 lb tank is not a "5 gallon tank" in the sense people mean, even though it is often labeled that way. It holds 4.6 gallons, and that 0.4-gallon difference matters when you are comparing cost per gallon against an exchange cage that only gives you 15 lb.

Burn Time by Appliance

Every number below is 430,000 BTU divided by the appliance's rated input. Ratings come from specifications, but treat them as the top of a range: a burner turned to medium uses less, and a cold tank delivers less.

• Single-burner camp stove, 10,000 BTU → about 43 hours. That is 2-3 seasons of weekend coffee and oatmeal.
• Two-burner camp stove, 20,000 BTU (both burners full) → about 21 hours. Realistically you rarely run both wide open, so plan 25-30 hours of mixed cooking.
• Tabletop grill, 11,000-15,000 BTU → 29-39 hours. A 20 lb tank turns a weekend grill into something you stop thinking about.
• Full-size gas grill, 30,000 BTU → about 14 hours at full heat, closer to 20 hours at medium.
• Blackstone-style 22-inch griddle, 24,000 BTU → about 18 hours. Breakfast for eight, both mornings, and you have barely moved the needle.
• Buddy heater, 4,000-9,000 BTU → 48 hours on high, and longer in low mode. This is the appliance that changes your refill schedule.
• Big Buddy, 18,000 BTU → about 24 hours on high.
• RV furnace, 30,000 BTU → about 14 hours of continuous run. A furnace cycles, so a cold night might use 3-5 hours of actual burner time — but two cold nights in a row will visibly drop the tank.
• Portable fire pit, 40,000-60,000 BTU → 7-11 hours, the thirstiest thing most campers own.
• Propane generator → 5-11 hours, and worth its own explanation below.

How Long Will a 20 lb Propane Tank Last on a Generator?

Long enough to be useful, short enough to surprise you. A propane generator's published consumption typically runs 0.4-0.9 gallons per hour depending on load, which puts a 4.6-gallon tank at roughly 5 to 11 hours:

• At quarter load (a fridge, lights, phone chargers — call it 0.4 gal/hr) → about 11 hours
• At half load (adding a well pump or a space heater — around 0.7 gal/hr) → about 6-7 hours
• At full load (0.9 gal/hr and up) → about 5 hours

Two things follow. First, a 20 lb tank is a one-night power source for anything but light loads; if you are planning a multi-day outage, plan on two tanks or a larger cylinder. Second, propane generators are quieter and don't need a fuel stabilizer, but they burn through fuel faster than a comparable gasoline unit holds in its small tank — so the tank count, not the generator, is what you pack around.

Cold Weather: Why the Tank Slows Down Before It's Empty

This is the part that makes people think their tank is broken. Propane is a liquid that has to boil into vapor before it burns, and cold slows that boil down.

• At 70°F, a 20 lb tank's vapor pressure is about 110 psi — plenty for any camping appliance.
• At 32°F, it is about 55 psi.
• At 0°F, it is about 24 psi, and the tank's ability to vaporize fuel drops to roughly 40,000-45,000 BTU/hr. That is still enough for a camp stove, and it is not enough to feed a 50,000 BTU fire pit or a big three-burner grill.
• Below about -20°F, a 20 lb tank can struggle to supply even a Buddy heater at full output.

What this looks like in the field: the flame gets lazy, the heater's pilot drops out, and the tank feels half full when it is nearly full. The fix is physics, not equipment — keep the tank warmer than the air. Set it out of the wind, off the cold ground (a scrap of foam or a board works), and never bring a tank inside a tent or a closed vehicle to "warm it up." A tank that warms in a sealed space is exactly how fuel fires start, and our heater safety guide covers the tent rules in detail.

One comfort: a 20 lb tank handles cold far better than a 1 lb canister, because there is more liquid surface area and more thermal mass. If you camp into November or December, upsizing the tank is the single biggest fuel fix available to you — the cold-weather stove guide covers the appliance side of the same problem.

How to Tell How Much Propane Is Left

Two methods work, and one of them is free.

1. Weigh it. Put the tank on a bathroom scale. Subtract the stamped TW on the collar (usually 17-18 lb). The remainder is your propane, in pounds. A reading of 37 lb is a full tank; 27 lb is half; 22 lb means you have about 4-5 hours of camp-stove cooking left. This is the only measurement that cannot lie.

2. Read a gauge. A DOZYANT propane tank gauge ($15.99, 4.4★ from 5,954 owners) threads between the tank and the regulator, reads the level as the tank sits, and doubles as a leak-down indicator. It is not lab-accurate near the bottom of the tank — pressure stays nearly flat until the fuel is genuinely low, which is why gauges "drop suddenly" — but for answering "am I refilling this weekend?" it is the tool you want.

The hot-water trick is a decent field check: pour a cup of hot water down the side of the tank and run your hand down it. The fuel line shows up as the cold spot, because liquid propane absorbs heat. It is crude, but it never runs out of batteries.

Whatever you use, pair it with a real leak check. A TECHAMOR Y201 Pro gas sniffer ($25.99, 4.4★) alarms on propane at the connection in about ten seconds — worth doing once a season, and mandatory before you trust a refilled tank on a trip. The canister and cylinder safety guide walks through the full connection check.

Refill, Exchange, or Burn 1 lb Bottles?

The tank is the cheap part. The fuel is where the money goes, and the three routes are not close:

• Exchange cage: about $25 for a tank that is filled to 15 lb, not 20. That is roughly $1.67 per pound — and you are also trading in your tank each time, so you inherit whatever condition the cage has.
• Refill at a station or propane dealer: about $20-25 for a full 20 lb fill, or roughly $1.00-1.25 per pound. Cheaper per pound and you keep your own cylinder.
• 1 lb disposable bottles: about $300 per million BTU versus roughly $47 for a 20 lb refill — roughly 6× the cost per unit of heat. If you cook more than a weekend a month, the crossover is obvious.

That crossover math is the subject of its own breakdown in 1 lb vs 20 lb: what each trip actually costs, including the adapter you need to run a 20 lb tank on a 1 lb stove. Two pieces of hardware make the switch cheap: a Gas One refill adapter with hose ($14.99, 4.5★) to refill your own small cylinders from a bulk tank, and a GASPRO 20 lb to 1 lb converter ($9.98, 4.6★) to feed a bottle-top stove straight off the big tank.

If you would rather not refill disposables at all — the legal reading varies by state — a Flame King refillable 1 lb cylinder with refill kit ($59.99, 4.6★) is the DOT-compliant route, and the 1 lb refill guide covers the process step by step.

What a Family Weekend Actually Uses

Burn-time tables are abstract. A real weekend looks like this for a family of four:

• Saturday breakfast: bacon, pancakes, coffee on a two-burner stove — about 45 minutes of flame at ~15,000 BTU total → ~11,000 BTU
• Saturday dinner: chili and rice, 40 minutes at ~10,000 BTU → ~7,000 BTU
• Sunday breakfast: repeat → ~11,000 BTU
• Coffee and hot chocolate, both evenings → ~4,000 BTU
• Buddy heater, both nights, 4 hours on high → ~72,000 BTU

Total: roughly 105,000 BTU, or about a quarter of a 20 lb tank. That is four weekends of cooking and heating per tank, which lines up with the "one tank per season" rule of thumb most car campers land on after their first year. Drop the heater and the same tank stretches to a dozen weekends.

Two practical notes: pre-cook at home what you can (chili, rice, potatoes), and shut the stove off between tasks. Those two habits cut fuel use by about a third, and they are the same habits that make a 1 lb canister last longer. If you are sizing fuel for a specific trip, the propane calculator returns hours and cost from your burner's BTU rating, and the how much propane for camping guide covers the per-day planning math.

When a 20 lb Tank Is the Wrong Answer

• Backpacking. A 20 lb tank is 37 lb full. Isobutane canisters exist for a reason.
• Trips under about 200 miles in a sedan. A full tank is heavy, and it must ride upright and secured. The storage and transport guide covers the valve cap, the upright rule, and what "never in a trunk" actually means.
• Hard freezes below -20°F. Vaporization, not fuel, becomes the limit. A heated tent or a wood stove is the right tool — see the hot tent guide.
• Air travel and most rental RVs. You cannot fly with it, and many rentals forbid customer tanks.
• One-night trips with a bottle-top stove. A Coleman Bottle Top ($21.99, 4.5★ from 12,600 owners) and a 12-pack of 16.4 oz cylinders ($64.99, 4.8★) is simpler than hauling a bulk tank for two meals. The 12-pack is roughly 26 hours of full-blast cooking — about a season of light use.

For grills specifically, the runtime math is the same but the heat delivery is not: a Coleman RoadTrip 225 ($199.99, 4.5★) runs on a 1 lb bottle for a single dinner or on a 20 lb tank through an adapter hose for a whole weekend, which is the setup most families eventually build. Our camping grill guide compares the propane options directly.

Common Mistakes With a 20 lb Tank

1. Buying a 20 lb tank for a 1 lb stove and no adapter. The tank has a QCC1 valve; the stove has a 1 lb connector. Without a hose or a converter, the tank does not connect to anything.
2. Storing it on its side or in a hot shed. Liquid propane has to sit over the valve. Upright, capped, out of the sun, on a hard surface.
3. Judging fuel by shaking. Liquid sloshes and vapor doesn't, so a shake tells you almost nothing on a partly used tank. Weigh it.
4. Refilling past the OPD stop. The valve is a safety device, not a suggestion. A tank with no headspace vents propane the first warm day.
5. Assuming exchange tanks are full. They are 15 lb. That is 25% less fuel than the "20 lb" name implies, and it is the single most common reason people think propane got more expensive.
6. Ignoring the connection. Most "my tank is empty" complaints are a bad O-ring or a loose regulator, not fuel. A sniffer test costs ten seconds. Our hose, regulator and adapter guide covers the fittings, and a Mr. Heater 10-foot hose assembly ($17.99, 4.6★) lets you keep the tank outside the tent where it belongs while the heater runs inside.
7. Running a heater unattended overnight. A Mr. Heater Buddy ($74.00, 4.7★ from 25,065 owners) has a low-oxygen shutoff, and it still belongs in a ventilated space with a CO alarm, not a zipped-up tent.

FAQ: 20 lb Propane Tank Run Time

How long does a 20 lb propane tank last?

About 43 hours on a 10,000 BTU camp stove, 21 hours with two burners at full output, 14 hours on a 30,000 BTU grill, and 48 hours on a 9,000 BTU Buddy heater. Every one of those numbers comes from the same 430,000 BTU of fuel divided by a different burn rate — so the appliance, not the tank, decides.

How many gallons does a 20 lb propane tank hold?

4.6 gallons of propane when filled to the OPD limit. Propane weighs about 4.24 lb per gallon, so 20 lb ÷ 4.24 = 4.7 gallons of capacity, of which the valve allows 80% fill. Exchange-cage tanks typically hand you 15 lb, or about 3.5 gallons.

How long will a 20 lb propane tank last on a grill?

14 hours at 30,000 BTU on a full-size grill, or 29-39 hours on an 11,000-15,000 BTU tabletop grill. Most people grill at medium rather than wide open, so the practical number sits in the upper half of those ranges. A 22-inch griddle running 24,000 BTU gets about 18 hours.

How long does a 20 lb propane tank last on a generator?

Roughly 5 to 11 hours, depending on load. Published consumption for propane generators runs about 0.4-0.9 gallons per hour, and a 20 lb tank holds 4.6 gallons. Light loads (fridge, lights, chargers) land near 11 hours; adding a heater or a pump drops it to 6-7.

Does a 20 lb tank last longer in warm weather?

Yes, and not because the fuel changes. Warm propane vaporizes faster: a 20 lb tank at 70°F holds about 110 psi of vapor pressure versus about 24 psi at 0°F, when vaporization limits a 20 lb tank to roughly 40,000-45,000 BTU/hr. In deep cold the appliance starves before the fuel runs out.

How do I know when a 20 lb propane tank is empty?

Weigh it. A full tank is about 37-38 lb, the stamp on the collar (TW) is 17-18 lb, and the difference is your propane. At 22 lb total you have a few hours of camp-stove cooking left. A gauge like the DOZYANT level indicator gives a fast read without a scale, and the hot-water trick works when neither is handy.

How long does a 20 lb tank last on a family camping weekend?

About four weekends if you cook three meals a day on a stove and run a propane heater for four hours a night, or roughly a dozen weekends of cooking-only use. A typical weekend of six meals plus two heated evenings lands near 105,000 BTU — a quarter of the tank.

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