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Fuel Cost Calculator
Calculate trip fuel cost in seconds. Works in US units (miles/mpg/$/gal) and metric (km/L per 100km/$/L). See total cost, fuel used, and cost per mile or km.
About This Calculator
Find out exactly how much a road trip will cost in gas. Enter the distance, your vehicle's fuel efficiency, and the current gas price — the calculator shows total cost, fuel consumed, and cost per mile or kilometre. Supports both US (mpg) and metric (L/100km) units.
How It Works
Choose US or metric units, then enter distance, fuel efficiency, and price per gallon (or litre). The calculator computes fuel used and multiplies by the price. US: fuelGallons = distance ÷ mpg. Metric: fuelLitres = distance × (L/100km) ÷ 100. Mixed-unit pairs (km with mpg) are prevented by the unit-system toggle — always use the same unit system end-to-end.
The Formula
US: cost = (distance ÷ mpg) × price/gal Metric: cost = (distance × L/100km ÷ 100) × price/L
- distance
- trip distance in miles (US) or km (metric)
- mpg
- vehicle fuel efficiency in miles per gallon
- L/100km
- vehicle fuel consumption in litres per 100 km
- price
- fuel price per gallon (US) or per litre (metric)
Frequently Asked Questions
- What is my car's mpg?
- Check your vehicle owner's manual or the EPA fuel economy label. You can also look up your year/make/model at fueleconomy.gov for the official EPA estimate.
- Can I mix miles with L/100km?
- No — always use a consistent unit system. The calculator prevents this by locking all units to either US or metric when you choose the unit system at the top.
- How do I convert my car's L/100km rating to mpg?
- mpg ≈ 235.214 ÷ L/100km. For example, 7 L/100km ≈ 33.6 mpg.