Gas Mileage Calculator
Calculate your vehicle's fuel efficiency in miles per gallon (US/UK), kilometers per liter or liters per 100 km — from trip distance and fuel used.
How to use the Gas Mileage Calculator
- Enter your inputs into the Gas Mileage Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The fuel efficiency formulas
MPG = Miles / Gallons used · · · L/100km = (Liters × 100) / km · · · km/L = km / Liters
MPG is the US standard; L/100km is European; km/L is used in Asia and Latin America. Higher MPG = more efficient. Lower L/100km = more efficient (counter-intuitive direction).
Worked example
Drove 380 miles, refueled 12.5 gallons: MPG = 380/12.5 = 30.4. In metric: 12.5 gal = 47.3 L; 380 mi = 611.5 km. L/100km = (47.3 × 100)/611.5 ≈ 7.74.
Frequently asked questions
What's a good MPG?
Compact gas cars: 30–40 MPG. Pickup trucks: 18–22 MPG. Hybrids: 45–55 MPG. EVs: 100+ MPGe (gasoline equivalent). Real-world MPG often runs 10–15% below EPA ratings.
Why is my actual MPG lower than the rating?
EPA tests are standardized lab conditions. Real driving includes city traffic, aggressive acceleration, AC use, cold starts, cargo and headwinds — all of which reduce efficiency.
How do I improve my MPG?
Drive 55–65 mph on highway, gentle acceleration, maintain tire pressure, remove unnecessary cargo, combine trips, keep up with maintenance (clean air filter, fresh oil).