Propane Tank Runtime Calculator
Pick a cylinder or tank and enter the burner's rated input. The result is how many hours one full fill runs the burner at full rate, plus the gallons and refills a season of use takes.
Result
Hours per full fill
8.6 h
- Propane in a full fill
- 4.7 gal
- Burn hours per season
- 104.0 h
- Propane per season
- 56.8 gal
- Fills per season
- 12.1
- Refills needed if you start the season full
- 12
Notes on This Result
- Cold weather and a low liquid level cut how fast a cylinder can turn liquid propane into gas, so a small cylinder can fail to keep up with a large burner before it is empty. We could not find a US primary source with limits for cylinders, so this tool gives no figure.
- A natural gas appliance converted to propane, or the reverse, needs the manufacturer's conversion kit and a qualified installer. Do not size runtime for a converted appliance from its original rating.
Calculation Details
Formula
Hours per fill = gallons in a full fill × 91,500 Btu per gallon ÷ burner input in Btu/h. Gallons per season = hours used × burner input ÷ 91,500.
Assumptions
- One gallon of propane holds 91,500 Btu (Propane Education & Research Council).
- The burner runs at its full rated input the whole time. Turning the flame down stretches the runtime.
- A full fill is the propane a cylinder is rated to hold, or 80% of an ASME tank's water capacity. Tanks are not filled to the top, because liquid propane expands when it warms.
- Runtime is counted to empty. In practice the last of the tank delivers less in cold weather, so plan your refill before it runs dry.
- Cold weather cuts how fast a tank can turn liquid into gas. A small cylinder can fail to keep up with a large burner on a cold night even when it still has fuel in it.
Sources
Propane Education & Research Council, The Propane Technical Pocket Guide (4482-BR-21 v3, PDF dated 2022-09-28), Table 1C 'Energy content and environmental impact of various energy sources', propane per gal: 91,500 Btu/gal, printed p. 5
Checked . View at cloudinary.propane.com.
Manchester Tank & Equipment Co., Portable DOT Steel LP Gas Cylinders 5 lb to 100 lb, Catalog 49500 (09/2022), row LPG CAPACITY (GAL), PDF p. 2. All capacities are nominal at 60°F
Checked . View at mantank.com.
Propane Education & Research Council, The Propane Technical Pocket Guide (4482-BR-21 v3, PDF dated 2022-09-28), Vaporization Rates, printed p. 9
Checked . View at cloudinary.propane.com.
What the Result Means
Hours per fill is figured at full flame. It assumes the burner runs at its full rated input from a full tank to empty. Most fire features run below full rate, and turning the flame down stretches the runtime, so the real figure is often longer. The last of a tank also delivers less in cold weather, so plan your refill before it runs dry.
The seasonal figures come from the hours, uses and weeks you enter. The defaults illustrate a half-year pattern. They are not a statistic, so replace them with your own.
Cold weather limits what a container can deliver. Vaporization falls with temperature and with the liquid level in the container, and a small cylinder can fail to keep up with a large burner before it is empty. We found no US primary source with limits for the 20 to 40 pound cylinders, so the tool gives no figure and says so. For larger ASME tanks it compares your burner with the continuous-loading withdrawal rate that PERC publishes for 250, 500 and 1,000 gallon tanks at 0°F, and warns when you are above it.
A household tank that also feeds a furnace or water heater is drawn down by those loads too, and the tool does not model that. It does not model a converted appliance either. If a natural gas unit has been converted to propane, or the reverse, do not size runtime from its original rating.
Call a propane supplier or a licensed installer for anything beyond swapping a cylinder. Setting an ASME tank, running a line from it, choosing regulators and placing the tank relative to buildings and openings is licensed propane work. PERC's guide gives placement distances, and this tool does not compute them.
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