Fuel Mileage Calculator

How to use the Fuel Mileage Calculator

What this calculator does

This calculator estimates how far a vehicle traveled per unit of fuel and, in the opposite direction, how much fuel it consumed per standardized distance. It uses the trip relationship fuel mileage = distance traveled ÷ fuel used, then converts that physical result into US mpg, km/L, UK mpg, L/100 km, and US gal/100 mi. If you also provide a fuel price, it estimates the fuel cost of the recorded trip. It does not predict laboratory-rated economy, traffic, maintenance condition, fuel quality, weather, or future driving behavior. The U.S. Environmental Protection Agency describes the same practical refill method: miles driven divided by gallons purchased at refueling; see the EPA's guidance on measuring real-world fuel economy.

When to use it

Use it after a full-tank-to-full-tank trip to estimate your own observed mileage, when comparing two routes or driving habits using separate trips, when checking whether fuel economy has changed over several refills, or when planning a rough fuel budget for a known trip. For vehicle-shopping comparisons, remember that measured trip mileage and standardized test ratings answer different questions.

How to calculate

1. The calculator opens with a ready-to-use demonstration: 310 miles, 10 US gallons, and $3.60 per US gallon. Its example Excel workbook is available immediately.
2. Replace Distance traveled with the distance covered. Choose miles or kilometers. Changing the distance unit converts the current value so the physical trip is preserved.
3. Replace Fuel used with the measured volume. Choose US gallons, liters, or UK gallons. The value converts when its unit changes.
4. Optionally enter Fuel price and choose its matching price unit. This calculator labels money as USD and converts the price per unit when the price unit changes; it does not fetch currency exchange rates.
5. Choose Primary mileage unit to make US mpg, km/L, or UK mpg the headline. Read the consumption and equivalent-unit results underneath, then use Download Excel to export the current validated state.
6. Reset clears the demonstration and all user-entered semantic data. The Excel button is then disabled until a complete valid distance-and-fuel state is entered again.

Input guide

Distance traveled is required and accepts a positive decimal number, optionally with correctly placed thousands commas and a decimal point. Example: 310 miles. Values must be greater than zero and no more than 1,000,000,000 in the selected distance unit. Increasing distance while fuel stays fixed raises fuel economy and lowers fuel consumption. Do not paste scientific notation or a decimal comma such as “1,5”; ambiguous formats are rejected rather than silently reinterpreted.

Distance unit is required and may be miles or kilometers. It changes the stored display quantity by exact unit conversion, not by merely relabeling it. Fuel used is required, uses the same numeric format rules, must be greater than zero, and may be US gallons, liters, or UK gallons. Example: 10 US gallons. More fuel for the same distance lowers mpg/km/L and raises L/100 km. A frequent measurement mistake is mixing a partial refill with a distance that spans more fuel than was actually added.

Fuel price is optional, accepts zero or a positive decimal number up to 1,000,000, and is interpreted as USD per the selected price-volume unit. Example: 3.60 USD/US gal. It changes Trip cost and Cost per 100 km but does not change fuel mileage. Price unit may be USD/US gal, USD/liter, or USD/UK gal; switching it converts the existing price to preserve the same price per physical fuel volume. Primary mileage unit changes only the headline representation among US mpg, km/L, and UK mpg.

Output guide

Fuel mileage is the primary distance-per-fuel result. Higher values mean more distance per unit of fuel. Fuel consumption is shown as L/100 km; lower values mean less fuel burned for the same standardized distance. Trip cost is fuel used multiplied by fuel price; it is “Not priced” when fuel price is blank. Cost per 100 km normalizes the trip's fuel cost by distance and is also unavailable without a price.

The Equivalent measures block reports US fuel economy, Metric fuel economy, UK fuel economy, and US consumption from the same canonical trip. The Conversion detail table has three columns: Measure names the representation, Value gives the converted number and unit, and How to read it explains whether the figure is distance-per-fuel or fuel-per-distance. These are exact unit transformations of the same calculated trip, not independent performance estimates.

Worked example

With the startup values, 310 miles ÷ 10 US gallons = 31.00 US mpg. Converting the same trip gives 13.18 km/L, 37.23 UK mpg, 7.59 L/100 km, and 3.23 US gal/100 mi. At $3.60 per US gallon, 10 gallons cost $36.00. Since 310 miles is about 498.90 km, the normalized fuel cost is about $7.22 per 100 km. These displayed values and the downloadable startup workbook come from the same trip model.