How long a propane tank lasts on a grill, computed

A full 20 pound tank runs a 30,000 BTU grill for roughly 14 hours with every burner wide open, and nobody cooks that way for long, so in practice it runs longer. A 15 pound exchange tank, which is what the swap cage at the store hands you, is nearer 10. On a 10,000 BTU portable the same 20 pound tank clears 40 hours, a whole season of tailgates. How long a propane tank lasts is division, not folklore, and the table below does the division for the common tank sizes and burner ratings. One reader should leave now: a grill on a plumbed natural gas line never runs dry, and the Weber Spirit E-325 review covers the factory natural gas version of that grill and who should choose it.

The hours in a tank, computed

Propane's energy content is a published number. EIA puts it at 91,452 Btu per gallon, and liquid propane weighs about 4.24 pounds to the gallon at 60°F, straight from NIST's published density. A tank's size is a weight of fuel, a burner's rating is an input in Btu per hour, and the hours on board are one division away. The table is computed from those two figures and assumes the burner runs wide open at its rated input from the first minute to the last.

Nobody grills at maximum for hours on end. Preheat happens there, most of the cooking does not, so treat every cell as a floor on a full tank rather than a forecast.

How to read the table against a real grill

Weber rates the Spirit E-325's three main burners at a combined 31,000 BTU per hour. A standard grill cylinder fills with 20 pounds of propane, which is about 430,000 Btu at the figures above. Divide, and the Spirit runs roughly 14 hours with all three burners flat out, just under the table's 30,000 BTU column because 31,000 burns a shade faster. The same grill on a 15 pound exchange fill gets a little over 10. The rating covers the three main burners only, so a cook that leans on the Sear Zone boost burners lands under the estimate.

Nameplate hours are not cooking hours. Half an hour with everything at maximum burns about 15,500 Btu, and a full tank covers that more than 25 times over. The floor is 14 hours. A summer of weekend cooks is the realistic read.

Why the exchange tank is 15 pounds, not 20

Blue Rhino answers this on its own FAQ: its exchange tanks contain a net 15 pounds of propane. The steel is built for more. A refill station fills by weight, the tare weight of the cylinder plus about 20 pounds of propane to bring a standard grill tank to capacity. A swap therefore hands you roughly three quarters of a full tank, which is exactly why the table carries a 15 pound row.

The trade is fuel for convenience. Exchange is the wrong choice for anyone with a refill station on a route they already drive: the same errand puts about a third more propane in the same tank. It is the right choice when the nearest refill is a special trip, or when the tank being handed over is rusted enough that losing it is the point.

How to check what is left in the tank

Weigh it. Every grill cylinder's collar is stamped with a tare weight, marked TW, the weight of the empty tank in pounds. Set the tank on a bathroom or luggage scale and subtract the TW. What remains is pounds of propane. A common 20 pound cylinder tares around 18 pounds and weighs about 38 pounds full, so a tank reading 28 on the scale with an 18 on the collar is holding 10 pounds, half its fill. Check it the day before the party, and the table turns those pounds into hours while there is still time to swap.

When a 1 lb cylinder is the right call

Portables, and very little else. A 1 lb camping cylinder threads straight into the regulator on gear built for it, no hose, no full-size tank riding in the trunk. That is most of the case for the Blackstone On The Go 22, which packs into a car with its fuel in a coat pocket. The table's top row is the discipline: 2.2 hours at 10,000 BTU and 1.1 at 20,000. That is a tailgate breakfast, not an afternoon of wings, and a second bottle weighs less than any other answer to running out.

A 1 lb bottle is the wrong fuel for a full-size grill and for any cook measured in half days. Where a grill maker lists an adapter hose for 1 lb bottles, that listed hose is the one way to connect one. Anything past a listed accessory, a different regulator, a bulk-tank tee, a plumbed line, is work for a licensed gas professional, not a parts order.

Common questions

Does a propane tank last longer on a low setting? Yes, in direct proportion to the gas going through the burner. A burner held at half its rated input burns half the propane per hour, so the hours double. The table assumes every burner wide open, which is why its cells read as floors instead of averages.

How should you store a propane tank? Outdoors, upright, and never inside a building, and a garage is a building. Fire code bars storing cylinders inside buildings, and official safety guidance adds the posture: outdoors, in an upright position. Give the spare a spot where nothing can tip it or heat it, which rules out the shelf under a lit grill.

Can you use a 1 lb bottle on a full-size grill? Only with an adapter hose the grill's maker lists for that exact model. A full-size grill's regulator is designed around a 20 pound tank, and the maker's listed hose is the one tested path to anything smaller. Past that listing sits conversion territory, and conversions belong to a licensed gas professional.

Should you refill a tank or exchange it? Refill when a station sits on a route already driven, exchange when it does not. A refill by weight brings a standard grill tank to about 20 pounds of propane, an exchange hands over 15, and the grill itself cannot tell the difference in anything except hours.

The tank is the solved half of the decision. If the grill is still open, the gas grills hub holds specs and current prices for everything this table applies to. If the question underneath is whether propane is the right fuel at all, pellet vs electric vs propane for a smoker weighs what each fuel asks of an owner, and the Masterbuilt 40-inch ThermoTemp review covers the tank-fed smoker those long afternoons run through, fuel gauge on the regulator included.