Fuel Range Remaining Calculator
Estimate how far you can drive on the fuel left in the tank from your fuel economy, with a safety reserve you keep untouched.
How it works
Range to empty = fuel remaining × mpg · Usable = max(0, remaining − reserve) · Safe range = usable × mpg
Driving range is simply the fuel you have multiplied by how far each gallon takes you. Because running a tank truly dry risks stranding you and can draw sediment or air into the fuel system, it is wise to hold back a small reserve — this calculator shows both the theoretical range to empty and the safer range that leaves a buffer. Real economy drops in city traffic, cold weather, at high speed and when carrying loads or towing, so treat the estimate as an upper bound and refuel with margin to spare.
Worked example
You have 4 gallons left and average 28 mpg. Range to empty is 4 × 28 = 112 miles. Keeping a 1-gallon reserve leaves 3 usable gallons, giving a safer range of 3 × 28 = 84 miles.
Frequently asked questions
How accurate is the range shown on my dashboard?
The car’s “distance to empty” is an estimate based on recent driving, so it can swing widely if your conditions change — a highway average will overstate range once you hit city traffic or a headwind. This calculator lets you plug in a realistic mpg and a reserve for a more conservative figure.
Is it bad to run the tank very low?
Regularly running near empty can let the fuel pump run hot (it is cooled by surrounding fuel) and may draw in tank debris. Keeping a reserve of a gallon or two is easier on the fuel system and gives a safety margin if the next station is farther than expected.
Why is my real range lower than calculated?
Rated or highway mpg rarely matches real driving. Cold starts, short trips, city stop-and-go, high speeds, roof racks, heavy loads and towing all cut economy, sometimes by 20–40%, which shortens your true range accordingly.
Related calculators
Educational estimate — real figures vary by vehicle, load, conditions and manufacturer specs. Always follow your owner’s manual.