Propane Tank Runtime Calculator

Estimate how long a propane tank will last.

Propane in tank

gal

Appliance BTU rating

BTU/h

Results update as you type.

Estimated runtime

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How it works

Estimating how long a propane tank will power an appliance helps you plan for grilling, heating, and camping, and this calculator does it. You enter the amount of propane in the tank in gallons and the appliance's BTU-per-hour rating, and it returns the estimated runtime in hours. The calculation uses the energy content of propane, about 91,502 BTU per gallon, multiplying it by the gallons in your tank to get the total energy available, then dividing by how fast your appliance consumes energy, its BTU rating. A higher-BTU appliance, like a large heater or high-output burner, drains the tank faster than a small one. For reference, a standard 20-pound barbecue propane tank holds roughly 4.6 gallons when full, and larger residential tanks hold much more. Appliance BTU ratings are printed on the unit or in its manual; a typical grill burner might be 30,000 to 60,000 BTU, a patio heater around 40,000, and a home furnace much higher. This is an estimate assuming the appliance runs continuously at its rated output; real usage varies with settings, cycling, and efficiency, and cold weather can affect tank performance. Use it to know when to refill and avoid running out mid-cookout or on a cold night. Enter the propane amount and appliance BTU to estimate the runtime.

Formula

Runtime = (gallons × 91,502 BTU/gal) / appliance BTU per hour

One gallon of propane contains about 91,502 BTU of energy. The calculator multiplies the gallons in the tank by this energy content to get the total available BTU, then divides by the appliance's BTU-per-hour rating to find how many hours it can run. A higher BTU appliance burns through the propane faster.

Source:Propane energy content

We review all our tools from time to time to ensure accuracy.

Worked example

Propane in tank:20Appliance BTU rating:30000

(20 × 91,502) / 30,000 ≈ 61 hours of continuous use.

How to use this calculator

1
Enter your values
Enter propane in tank and appliance btu rating.
2
Adjust the options
Fine-tune any options to match your situation.
3
Read your result
Estimated runtime updates instantly as you type — no button to press.

Frequently asked questions

How long will my propane tank last?

Multiply the gallons of propane by about 91,502 BTU per gallon for the total energy, then divide by your appliance's BTU-per-hour rating. A 20-gallon supply running a 30,000 BTU appliance lasts about 61 hours of continuous use. The calculator does this from your tank size and appliance rating.

How many BTU are in a gallon of propane?

A gallon of propane contains about 91,502 BTU of energy. This is the standard figure used to convert a volume of propane into available energy. Multiplying the gallons in your tank by this number gives the total BTU you have to work with before dividing by your appliance's consumption rate.

How much propane is in a standard tank?

A common 20-pound barbecue tank holds about 4.6 gallons of propane when full, though tanks are usually filled to about 80 percent for safety. Larger tanks for homes and RVs hold much more, from 30-pound portable tanks up to 500-gallon or larger stationary tanks. Enter the actual gallons available for an accurate runtime.

Where do I find my appliance's BTU rating?

The BTU-per-hour rating is usually printed on a label on the appliance or listed in its manual and specifications. A grill burner might be 30,000 to 60,000 BTU, a patio heater around 40,000, and a furnace much higher. Use the total rating if an appliance has multiple burners running at once.

Is the estimate exact?

It is an estimate assuming the appliance runs continuously at its full rated output. Real runtime varies: appliances often cycle on and off or run below maximum, which extends the time, while cold weather can reduce tank pressure and performance. Use the estimate as a guide for planning refills, with some margin to avoid running out.