Grills and Griddles
Propane Tank Burn Time Chart: Hours by BTU and Tank Size
Quick answer
A full 20 lb propane tank holds about 431,000 BTU. A 30,000 BTU grill runs about 14.4 hours on high, a 46,000 BTU patio heater about 9.4 hours, and a 60,000 BTU griddle about 7.2 hours. At half throttle, double each figure.
Propane runtime is arithmetic once you know two numbers: the energy in the tank and how fast the appliance burns it. One pound of propane holds about 21,548 BTU, so a full 20 lb tank holds roughly 431,000 BTU.
Find your appliance BTU rating on its label or in the manual, then read across. The propane tank runtime calculator handles partly full tanks and throttle settings. Our top pick among the high-BTU appliances people ask about is the Blackstone 36 in griddle with hood at $539.99.
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How long does a 20 lb propane tank last?
Most cooking happens around half throttle. Heaters and fire pits usually run at or near full output.
| Appliance | BTU per hour | 20 lb on high | 20 lb at half | 1 lb on high |
|---|---|---|---|---|
| Tabletop patio heater | 11,000 | 39.2 hr | 78.4 hr | 2.0 hr |
| Tabletop griddle, 1 burner | 12,000 | 35.9 hr | 71.8 hr | 1.8 hr |
| Portable heater on high | 18,000 | 23.9 hr | 47.9 hr | 1.2 hr |
| Small portable grill, 2 burner | 20,000 | 21.5 hr | 43.1 hr | 1.1 hr |
| Portable griddle, 2 burner | 24,000 | 18.0 hr | 35.9 hr | 0.9 hr |
| 3-burner gas grill | 30,000 | 14.4 hr | 28.7 hr | 0.7 hr |
| Propane fire pit table | 40,000 | 10.8 hr | 21.5 hr | 0.5 hr |
| Mushroom patio heater | 46,000 | 9.4 hr | 18.7 hr | 0.5 hr |
| 4-burner gas grill | 48,000 | 9.0 hr | 18.0 hr | 0.4 hr |
| Propane fire bowl | 58,000 | 7.4 hr | 14.9 hr | 0.4 hr |
| 36 in griddle, 4 burners | 60,000 | 7.2 hr | 14.4 hr | 0.4 hr |
| 6-burner grill with side burner | 72,000 | 6.0 hr | 12.0 hr | 0.3 hr |
Hours = pounds of propane x 21,548 / (rated BTU per hour x throttle). The rated BTU is the total for all main burners on high.
How much propane is in each tank size?
| Tank | Gallons (approx.) | BTU when full | Hours at 46,000 BTU |
|---|---|---|---|
| 1 lb cylinder | 0.2 | 21,548 | 0.5 hr |
| 11 lb tank | 2.6 | 237,028 | 5.2 hr |
| 20 lb tank | 4.7 | 430,960 | 9.4 hr |
| 30 lb tank | 7.1 | 646,440 | 14.1 hr |
| 40 lb tank | 9.4 | 861,920 | 18.7 hr |
| 100 lb cylinder | 23.6 | 2,154,800 | 46.8 hr |
Propane weighs about 4.24 lb per gallon. Tanks are filled to about 80 percent of volume to allow for expansion, and the stamped tare weight on the collar is the empty weight.
What does each appliance cost in propane hours?
| Appliance | Rated BTU | 20 lb tank on high |
|---|---|---|
| Cuisinart tabletop patio heater | 11,000 | 39.2 hr |
| Mr. Heater Big Buddy PRO | 18,000 | 23.9 hr |
| Camp Chef Gridiron Gameday 24 | 24,000 | 18.0 hr |
| Hiland pyramid patio heater | 40,000 | 10.8 hr |
| Endless Summer fire pit table | 40,000 | 10.8 hr |
| Broil King Baron 520 Pro | 45,000 | 9.6 hr |
| Amazon Basics 46,000 BTU heater | 46,000 | 9.4 hr |
| Pit Boss Ultimate 4-burner griddle | 46,000 | 9.4 hr |
| Nexgrill 4-burner | 48,000 | 9.0 hr |
| Fire Sense 61130 patio heater | 48,000 | 9.0 hr |
| Outland Firebowl 883 Mega | 58,000 | 7.4 hr |
| Blackstone 36 in 4-burner griddle | 60,000 | 7.2 hr |
| Broil King Regal S 690 Pro IR | 60,000 | 7.2 hr |
| Pit Boss Deluxe Fold and Go | 62,000 | 7.0 hr |
BTU figures are the published ratings for these models. Side burners and sear burners add to consumption only when lit.
How is propane runtime calculated?
The formula is hours = pounds of propane x 21,548 / (rated BTU per hour x throttle fraction). A 4-burner grill rated at 48,000 BTU run at about half output uses 24,000 BTU an hour, so a full 20 lb tank lasts 431,000 divided by 24,000, about 18 hours of cooking. At 45 minutes a cook, that is roughly 24 cooks per tank.
Two things bend the formula in the real world. Cold weather lowers the pressure a tank can deliver, and wind pulls heat off a cooking surface so you run burners higher for the same result. Both push winter consumption above the calculated figure. A partly used tank obviously holds less: weigh it and subtract the tare weight stamped on the collar.
How can I tell how much propane is left?
Weighing is the only reliable method. Subtract the tare weight stamped on the collar, usually around 17 lb for a 20 lb tank, from the current weight, and the difference is pounds of propane remaining. Multiply by 21,548 for the BTU left. A digital tank scale at $15.38 reads it directly, and the Bluetooth version reports to a phone.
Inline pressure gauges are less precise, because propane pressure tracks temperature rather than fill level until the tank is nearly empty. The warm-water trick, pouring warm water down the side and feeling for the cool line, gives a rough level with no tools. The simplest fix of all is a full spare, such as the Flame King 20 lb tank with gauge.
Is a 1 lb cylinder or a 20 lb tank cheaper to run?
A 20 lb tank is far cheaper per BTU. Disposable 1 lb cylinders cost several times more per pound of propane than a refilled 20 lb tank, and a 1 lb cylinder runs a 12,000 BTU tabletop griddle for only about 1.8 hours on high. For anything used at home rather than carried into the backcountry, an adapter hose such as the Gas One 4 ft adapter at $10.88 pays for itself quickly, provided the appliance manufacturer allows it.
Refilling is also usually cheaper than exchanging, because exchange tanks are often filled to about 15 lb rather than a full 20. That difference is roughly 108,000 BTU, or more than two hours of a 46,000 BTU heater.
Which propane gear is worth owning?
A spare tank, a way to measure what is left and an adapter hose cover almost every propane annoyance. Appliance picks are in the best gas grills and the best patio heaters.
Flame King YSN230 20 lb Propane Tank with Gauge
$69.99A full 20 lb tank with a gauge, which is the only real fix for running out mid-cook. A full tank holds about 431,000 BTU.
Best for: every propane grill and griddle owner
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Flame King Digital Propane Tank Scale
$15.38A digital scale reads remaining propane by weight, the only reliable method short of a built-in tank gauge.
Best for: knowing before a cook, not during
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Gas One 4 ft. 1 lb to 20 lb Propane Adapter Hose
$10.88Runs 1 lb cylinder appliances from a 20 lb tank, which cuts the cost per BTU several times over where the maker allows it.
Best for: tabletop griddles and portable heaters used at home
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Blackstone 36 in. Original Griddle with Built-in Hood
$539.99Four zones at about 60,000 BTU total, so small meals light two burners and use roughly half the fuel of a full burn.
Best for: families who cook outdoors weekly
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Amazon Basics 46,000 BTU Propane Patio Heater with Wheels
$162.74A 46,000 BTU mushroom heater empties a 20 lb tank in about 9.4 hours on high, which is two or three long evenings.
Best for: patios used after dark in shoulder seasons
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Bromic Tungsten Smart-Heat 4000W Electric Patio Heater
$693.70A 4,000W electric infrared heater avoids propane entirely where you have the circuit for it, with no refills to plan around.
Best for: covered patios with electrical capacity
Check price on AmazonHow we chose
We did not test these products in person. Picks are researched from manufacturer specifications and owner manuals, engine and safety certifications where they apply, warranty terms, public recall records, and the recurring themes in verified owner reviews. We favor established brands with large review counts and parts support, match each pick to a real yard size or task, and place it in the tier where its price and capability actually belong.
Frequently asked questions
How many hours of grilling do you get from a 20 lb propane tank?
Most people get 18 to 25 hours of grilling from a 20 lb tank. A typical 30,000 to 48,000 BTU grill run at medium uses 15,000 to 24,000 BTU an hour, and a full tank holds about 431,000 BTU. Run flat out on high, a 48,000 BTU grill empties the tank in about 9 hours. Cold weather, wind and long preheats shorten that.
How long does a 20 lb tank last on a Blackstone griddle?
A 36 inch four-burner rated around 60,000 BTU runs about 7.2 hours on a 20 lb tank with every burner on high, and about 14.4 hours at medium. Most griddle cooks light two or three zones, so 15 to 20 hours of real cooking per tank is common. A 17 or 22 inch tabletop on a 1 lb cylinder lasts roughly one to two hours.
How long does a 20 lb tank last on a patio heater?
A standard 46,000 to 48,000 BTU mushroom patio heater runs about 9 hours on high from a full 20 lb tank, and roughly 18 hours on low. A 40,000 BTU pyramid heater lasts about 10.8 hours on high. Because heaters usually run at full output all evening, plan on a fresh tank every two or three long evenings.
How much does a full 20 lb propane tank weigh?
An empty 20 lb tank typically weighs about 17 pounds, which is the tare weight stamped on its collar, so a full one weighs about 37 pounds. Subtract the tare weight from the current weight to get the pounds of propane left, then multiply by 21,548 to get the BTU remaining and divide by your appliance rating for hours.
Does a bigger grill use more propane?
Only when you light every burner. A six-burner rated at 72,000 BTU burns a tank in about 6 hours flat out, but lighting two burners for a small meal uses roughly the same fuel as a small grill. Heat retention matters more than burner count: a well-built grill reaches temperature at lower settings and holds it with less gas.
Researched, not professional advice. This page is compiled from published specifications, manuals, labels and owner-review consensus, not hands-on testing. Follow the manufacturer's instructions and product label, and consult a qualified professional where safety, chemicals, fuel or structures are involved. As an Amazon Associate we earn from qualifying purchases.