DIY Cost Tools
Fuel Range Calculator
AUTOMOTIVE CALCULATOR
Estimate driving range from available fuel, observed fuel economy, and a chosen reserve.
Use consistent units. All fields are required; absolute input values must not exceed one trillion. Range varies with traffic, weather, load, terrain, speed, and vehicle condition.
How to use this calculator
Replace the example inputs with your measurements, then select Calculate. Results use the units shown beside each field. Keep extra precision in the inputs and round only when recording the final answer.
Formula and explanation
Planning range = (available fuel − reserve fuel) × miles per gallon
The reserve is subtracted before calculating the distance you plan to drive. Enter observed fuel economy from similar conditions rather than relying only on a published rating.
Worked example
With Fuel available (US gallons) = 12, Fuel economy (miles/US gallon) = 28, Reserve fuel (US gallons) = 2, the results are Planning range after reserve (miles): 280; Theoretical total range (miles): 336; Reserve-equivalent distance (miles): 56.
Important limitations
Range varies with traffic, weather, load, terrain, speed, and vehicle condition. Fuel gauges are estimates. Keep a practical reserve and never rely on this tool to drive a tank empty.
Results are estimates based on the entered values. Numeric precision does not eliminate measurement uncertainty.
Frequently asked questions
Are the gallons US or imperial?
Use US gallons and miles per US gallon throughout. Convert imperial measurements first.
What reserve should I use?
Choose a reserve appropriate to your vehicle, route, weather, and access to fuel. This tool does not prescribe a safe minimum.
What happens if I leave a field blank?
The tool clears the previous result and asks for valid inputs, so an old answer is not mistaken for a new calculation.
Review notes
Reviewed October 1, 2026. Default calculations were checked independently against the displayed equations. The script validates blank, nonfinite, out-of-range, and formula-specific invalid inputs. Calculations run locally in your browser.