Math & Conversions

Fuel Economy Converter

Convert fuel economy between US MPG, liters per 100 km, and kilometers per liter. Enter a value and pick From and To units to get the converted figure.

What this calculator does

The Fuel Economy Converter estimates your result instantly from the values you enter, using standard math & conversions formulas. Convert fuel economy between US MPG, liters per 100 km, and kilometers per liter. Enter a value and pick From and To units to get the converted figure. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.

Fuel Economy Converter

Result

—
Converted Value

About Fuel Economy Converter

This converter moves a fuel-economy figure between three units: US miles per gallon, liters per 100 kilometers, and kilometers per liter. It first converts your input to km/L, then to the target unit.

Because L/100km is an inverse measure (lower is better) while MPG and km/L are direct (higher is better), the tool handles the reciprocal step for you.

Formula & Mathematical Calculation

Converted Value = f(Value, From, To)

Calculated according to standard math formulas implemented in the calculator core.

Calculation Example

Enter 30, From MPG (US), To L/100km. The tool converts 30 MPG to km/L (30 × 0.425144 = 12.75432 km/L), then to L/100km (100 ÷ 12.75432), giving 7.84 L/100km.

Key Benefits

  • Converts among MPG (US), L/100km, and km/L
  • Handles the inverse relationship of L/100km automatically
  • Accepts any positive economy value
  • Reports the converted value to three decimals

How to Use this Calculator

  1. Enter the value
    Type the fuel-economy number into the Value field.
  2. Choose From and To units
    Pick the input unit in From and the target unit in To.
  3. Calculate
    Select Calculate to read the Converted Value box.

Assumptions & Limitations

What the calculation assumes

  • Every value you enter is treated as an exact, known amount.
  • Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
  • Results use standard published formulas and account only for the values entered above.
  • Rounding is applied for display; the underlying calculation uses your full precision.
  • Results are returned in the same units you enter, unless the tool states the output unit.

What it does not cover

  • Fuel Economy Converter produces a calculated result for reference and learning, not a certified or official measurement.
  • Real-world outcomes differ when tolerances, rounding rules or local standards apply.
  • Definitions and standards vary by region and change over time; verify the convention that applies to your case.
  • Figures are only as accurate as the inputs you supply — check them before acting on the result.
  • For work where the result carries real consequences, confirm it against an authoritative source.

Frequently Asked Questions

US miles per gallon (MPG), liters per 100 kilometers (L/100km), and kilometers per liter (km/L).

Fuel economy of zero or below is not meaningful and would break the reciprocal used for L/100km, so the tool requires a positive value.

It uses the factor 0.425144 to move between US MPG and km/L before converting to the chosen output unit.

Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.