Fuel Cost Calculator – Trip Cost & Gas Mileage
Enter distance, efficiency, and fuel price — get fuel needed and total cost. Toggle US or metric and round-trip.
Planning a drive means knowing roughly how much fuel you’ll burn and what it will cost at the pump. Enter one-way distance, your real-world MPG or L/100km, and the local fuel price to get fuel volume and total cost instantly.
US mode uses miles and gallons (distance ÷ MPG). Metric mode uses kilometers and liters: liters = (L/100km ÷ 100) × km. Round trip doubles distance before the math. Nothing is sent to a server.
Timing a trip across days? Pair this with the Date Difference Calculator.
How to use
- Choose US (MPG, gallons) or Metric (L/100km, liters).
- Enter trip distance, your vehicle’s efficiency, and the fuel price.
- Turn on Round trip to double the distance for a there-and-back estimate.
- Read fuel needed and total cost. Use Reset to clear.
Tips
- Use real-world MPG or L/100km from a recent tank, not the sticker alone — highway vs city matters.
- Price should match the unit: $/gallon in US mode, price per liter in Metric mode.
- Round trip doubles distance only. It does not change MPG or fuel price.
- Hills, cold starts, cargo, and A/C can use more fuel than a steady highway estimate.
FAQ
How is fuel cost calculated?
US: gallons = distance ÷ MPG, cost = gallons × price per gallon. Metric: liters = (L/100km ÷ 100) × kilometers, cost = liters × price per liter. Round trip doubles distance first.
What is L/100km?
Liters per 100 kilometers — the common metric efficiency number. Lower is better (uses less fuel). It is the inverse idea of MPG, where higher is better.
How do I convert MPG to L/100km?
Roughly: L/100km ≈ 235.215 ÷ MPG. Example: 30 MPG ≈ 7.84 L/100km. Switch modes and enter the number your dash or owner’s manual uses.
Should I include a reserve?
This calculator estimates consumption for the distance you enter. For long trips, add a buffer for detours, traffic, or a spare gallon — especially in remote areas.
Does round trip include both directions equally?
Yes. It doubles your one-way distance. If the return uses a different route or efficiency, run two one-way calculations instead.
Is this accurate enough for budgeting a road trip?
It’s a solid planning estimate when your MPG/L/100km and local fuel price are realistic. Expect some variance from traffic, weather, and driving style.