How many hours of grilling are in a 20 lb propane tank?

A full 20 lb tank holds about 432,000 BTU. That is roughly 14 hours on a 30,000 BTU/hr grill, 10 to 11 hours on a 40,000 BTU/hr grill, and about 7 hours on a 60,000 BTU/hr grill — at full output. Cooking on medium gives more.

How many cookouts does a 20 lb tank give?

If a cookout is about an hour, a full 20 lb tank on a 40,000 BTU/hr grill is roughly 10 to 11 full-output cookouts, and often more because most people grill on medium. A 30,000 BTU/hr grill gets around 14.

Why is my exchange tank lighter than 20 lb of propane?

Many tank-exchange programs fill cylinders to about 15 lb of propane rather than the full 20 lb the tank can hold, to allow for expansion and to control cost. That means a 'full' exchange tank may give you up to a quarter less grilling time than a tank refilled to capacity.

How long does a 20 lb propane tank last?

The 20 lb tank is the standard exchange cylinder under most backyard grills. Here is exactly how much grilling it holds — and how to squeeze every cookout out of it.

Calculate my time

What a full 20 lb tank holds

A "20 lb" tank is named for the pounds of propane it carries when full — about 20 lb, or roughly 4.7 US gallons. Since propane releases about 21,594 BTU per pound, a full tank stores around 432,000 BTU of cooking energy. Divide that by your grill's burn rate and you get hours of grilling.

432,000 BTU ÷ grill BTU/hr = hours of grilling

~20 lb propane

About 4.7 gallons and 432,000 BTU in a properly filled tank.

7–14 hours

Full-output grilling, depending on your grill's total BTU rating.

~10–20 cookouts

For typical medium-heat, hour-long backyard sessions.

20 lb tank grilling time by grill size

Full tank, every burner on high — a conservative baseline. Cooking on medium stretches all of these further.

Grill output	Typical grill	Full-output time	~1 hr cookouts
26,000 BTU/hr	Small 2-burner	~16.6 hr	~16
30,000 BTU/hr	2-burner	~14.4 hr	~14
40,000 BTU/hr	3-burner	~10.8 hr	~11
50,000 BTU/hr	4-burner	~8.6 hr	~9
60,000 BTU/hr	Large 4–5 burner	~7.2 hr	~7

Want the figure for a half-full tank, or your own grill's exact BTUs? The calculator handles any combination and shows the math.

Exchange vs. refill: the hidden catch

Here is the thing most people miss. A 20 lb tank can hold 20 lb of propane, but many exchange programs only fill them to about 15 lb. You drop off an empty, grab a "full" one, and quietly lose up to a quarter of your grilling time. Refill stations, by contrast, fill to the tank's actual capacity by weight.

Refilling is usually cheaper per pound and gives you the full 20 lb — more cookouts per dollar.
Exchange is fast, available everywhere, and swaps out an aging tank for a recertified one, but you often pay more for less gas.
Check by weighing. A truly full tank weighs its tare weight (TW, ~17.2 lb) plus 20 lb — around 37 lb total. If your "full" exchange tank reads closer to 32 lb, it only has about 15 lb of propane.

How to know your 20 lb tank's real level

Weigh it. Total weight on a scale minus the stamped tare weight equals pounds of propane left. Enter both in the calculator's "Weigh the tank" mode.
Warm-water trick. Pour warm water down the side; the metal feels cool below the fuel line.
Keep a spare. The cheapest fix for "is there enough?" is a backup tank on the shelf.

Common questions

How many hours of grilling are in a 20 lb tank?

About 14 hours on a 30,000 BTU/hr grill, 10–11 hours on 40,000, and 7 hours on 60,000 — full tank, full output. Medium heat gives more.

How many cookouts is that?

For an hour-long session on a 40,000 BTU/hr grill, roughly 10–11 full-output cookouts, and commonly more in practice because most grilling is done on medium.

Why is my exchange tank lighter than expected?

Exchange programs often fill to about 15 lb instead of the full 20 lb, so a "full" swap tank can give up to a quarter less grilling time than a tank refilled to capacity.

Recommended gear

Get the most out of every 20 lb tank:

Propane tank scale — confirm a real 20 lb fill and track what is left.
Inline tank gauge — a quick level check before you start cooking.
Spare 20 lb tank — never get caught half-cooked.

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