Choose burn time, total fuel, or burn rate, then enter the two known positive quantities. Use kg, lb, metric tonnes, seconds, minutes, or hours; the calculator converts the selected units.
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Burn Time Formula
The burn time calculator uses the relationship between total fuel, burn rate, and time. Select the quantity to solve for, then enter the two known positive values.
- T = burn time
- F = total fuel
- R = burn rate
To calculate total fuel instead of burn time, the formula is rearranged:
To calculate burn rate, the formula is:
The calculator converts all inputs to base units before calculating: kilograms for fuel, kilograms per second for burn rate, and seconds for time. It then converts the result back to the unit you selected.
- Find burn time: use total fuel and burn rate to calculate how long the fuel lasts.
- Find total fuel: use burn rate and burn time to calculate how much fuel is required.
- Find burn rate: use total fuel and burn time to calculate fuel consumed per unit of time.
Fuel and Burn Rate Unit Conversions
These are the conversion factors used to keep the calculation consistent across different unit choices.
| Fuel unit | Equivalent in kilograms |
|---|---|
| 1 kilogram | 1 kg |
| 1 pound | 0.45359237 kg |
| 1 metric tonne | 1000 kg |
| Burn rate unit | Equivalent in kg/s | Common use |
|---|---|---|
| 1 kg/s | 1 kg/s | Direct metric burn rate |
| 1 lb/s | 0.45359237 kg/s | Imperial fuel flow |
| 1 metric tonne/h | approximately 0.277778 kg/s | Large hourly consumption rates |
Example Burn Time Calculations
Example 1: Calculate burn time
You have 50 kg of fuel and a burn rate of 2 kg/s.
The burn time is 25 seconds.
Example 2: Calculate total fuel needed
You need to burn fuel for 30 minutes at a rate of 0.5 kg/s.
First convert 30 minutes to seconds:
Then calculate total fuel:
The required fuel is 900 kg.
Burn Time Calculator FAQ
What does burn time mean?
Burn time is the amount of time a given quantity of fuel will last at a specific burn rate. If the burn rate stays constant, burn time is found by dividing total fuel by burn rate.
Why do the units matter?
The units must match before the formula is applied. For example, if fuel is in kilograms and burn rate is in kilograms per second, the burn time result is in seconds. If you use pounds, metric tonnes, minutes, or hours, the calculator converts the values first so the formula still works correctly.
Can burn rate change during real use?
Yes. This calculator assumes a constant burn rate. In real systems, burn rate may change with pressure, temperature, throttle setting, fuel quality, or operating conditions. If the burn rate changes over time, the result should be treated as an estimate.
