Fuel Efficiency Calculator

Enter distance and fuel used to calculate MPG or L/100km, and estimate the fuel cost for any trip.

Use the Fuel Efficiency Calculator

Fuel Efficiency Calculator

miles
gallons

Optional — Trip Cost Estimate

$ / gallon
miles

Enter distance and fuel used, then press Calculate.

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Summary

This tool calculates your vehicle's fuel efficiency from two inputs: distance traveled and the amount of fuel consumed. Switch between US customary units (miles + gallons = MPG) and metric units (kilometers + liters = L/100km). Enter a fuel price and a planned trip distance to get a real-time cost estimate.

How it works

  1. Choose your unit system — US customary (MPG) or Metric (L/100km).
  2. Enter the distance you traveled and the amount of fuel you used.
  3. The calculator instantly shows your fuel efficiency rating.
  4. Optionally enter fuel price per unit and a trip distance.
  5. The estimated fuel cost for that trip is displayed immediately.

Use cases

  • Track your car's fuel economy after every fill-up.
  • Compare efficiency before and after a tune-up or tire change.
  • Plan road-trip budgets by estimating total fuel cost.
  • Convert between MPG and L/100km for international comparisons.
  • Evaluate whether a newer, more fuel-efficient vehicle is worth buying.
  • Monitor fleet vehicles for unusual consumption spikes.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu