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Propane Tank Duration Calculator

Work out propane tank duration instantly with clear inputs, formula shown and shareable results.

About Propane Tank Duration Calculator

Propane carries about 91,500 BTU per gallon. Multiplying appliance input by the fraction of time it actually fires gives gallons per hour, and dividing the usable tank contents by that rate gives run time. Tanks are filled to 80 percent of water capacity to leave room for vapour expansion.

Formulas

Burn rate

gal/h = input BTU/h x duty cycle / 91500

Duration

hours = tank gallons x fill fraction / burn rate

Worked example

With the default values below, Propane Tank Duration Calculator returns Running time available of 305.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Tank water capacityminimum 1 gal
100 gal
Fill levelaccepts 1–80 %
80 %
Total appliance inputminimum 1 BTU/h
60,000 BTU/h
Average duty cycleaccepts 1–100 %
40 %

Results

Running time available
305.0 h
Days of supply
12.7 days
Usable propane
80.0 gal
Average daily use
6.30 gal/day

Step by step

  1. 1Values used
  2. 2Burn rate
  3. 3Duration
  4. 4Running time available= 305.0 h
  5. 5Days of supply= 12.7 days
  6. 6Usable propane= 80.0 gal
  7. 7Average daily use= 6.30 gal/day

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Propane Tank Duration figure worked out?

gal/h = input BTU/h x duty cycle / 91500. Propane carries about 91,500 BTU per gallon.

Why is the tank never filled past 80 percent?

Liquid propane expands about 17 times more than water for the same temperature rise. The vapour space absorbs that expansion and prevents the relief valve lifting on a hot day.

What values do I need to enter?

This calculator takes 4 inputs: Tank water capacity, Fill level, Total appliance input, Average duty cycle. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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