Fuel tank range calculator
Enter the size of the tank, how full it is and your car's consumption. The calculator gives the fuel on board, the theoretical range to empty and a safer range that stops at the reserve you want to keep.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric or US units.
- Enter the tank capacity and how full it is now, in percent.
- Enter your real average consumption.
- Set the reserve you want to keep.
How it works
- Fuel on board = tank × level ÷ 100.
- Range to empty = fuel ÷ consumption (L/100 km: × 100; mpg: × mpg).
- Usable range uses the fuel above the reserve; if the level is already below the reserve, it is zero.
Worked example
A 50 L tank, full, at 7.5 L/100 km: 50 ÷ 7.5 × 100 = 666.7 km to empty. Keeping a 10% reserve leaves 45 L, so 600 km usable. In US units, 13 gallons at half a tank and 30 mpg is 6.5 gal × 30 = 195 miles, or 156 miles above a 10% reserve.
Tips
- Use your trip average, not the brochure number.
- Motorway driving at higher speeds usually raises consumption.
- Plan stops before the usable range ends, not at zero.
Frequently asked questions
How is the range calculated?
Fuel on board = tank capacity × level. In metric units range = fuel ÷ consumption × 100 (consumption in L/100 km); in US units range = gallons × mpg. The usable range does the same with the fuel above your reserve level.
What tank capacity should I use?
The figure in your owner's manual or on the manufacturer's page for your exact model. Some of it may be unusable, which is one reason to keep a reserve.
Why keep a reserve?
Consumption varies with speed, load, weather and traffic, and fuel stations are not always where you expect. A reserve of 10% is a common habit, not a rule; set the figure you are comfortable with.
Is the fuel gauge accurate enough to use for the level?
Gauges are approximate, especially near full and near empty, so treat the result as an estimate and refuel with margin on long or remote drives.