Estimate the fuel cost of a trip. This free fuel cost calculator uses your distance, fuel economy and fuel price – in US or metric units – to show total cost, fuel used and cost per mile or kilometre.
Enter the trip distance, your vehicle’s fuel economy and the fuel price. Tick “round trip” to double the distance for a there-and-back journey.
Fuel cost = (distance / fuel economy) x fuel price. Use your real-world economy for the most accurate figure – actual mileage varies with driving style, load, terrain and weather.
What This Fuel Cost Calculator Does
This calculator estimates the fuel cost of a trip from distance, fuel economy, and fuel price, in either US units (miles, MPG, price per gallon) or metric units (kilometres, L/100km, price per litre). A round-trip option doubles the distance automatically.
The Core Formula
US: fuel used = distance / MPGMetric: fuel used = distance / 100 x L/100kmCost = fuel used x fuel price
A 300-mile trip at 30 MPG and $3.50 per gallon uses 10 gallons and costs exactly $35 – about $0.117 per mile, or $11.67 per 100 miles.
Why Real-World Fuel Economy Matters
Using your vehicle’s actual observed fuel economy (rather than the manufacturer’s rated figure) gives a more accurate cost estimate, since real driving conditions – traffic, terrain, weather, cargo weight – typically produce somewhat different fuel economy than laboratory test conditions.
Why the Round-Trip Option Matters for Planning
Many people search for a one-way distance (like “how far is it to X”) without remembering they’ll also need to drive back – the round-trip checkbox handles this automatically, avoiding a cost estimate that’s half of what a trip will actually require.
US vs Metric: Why Both Are Included
Fuel economy is measured completely differently in US and metric systems – MPG (higher is better) versus L/100km (lower is better) – so this calculator switches its entire formula and labeling based on which system you select, rather than just relabeling units.
How to Use the Fuel Cost Calculator
- Choose US or metric units.
- Enter your trip distance, fuel economy and fuel price.
- Tick round trip if driving there and back.
Want a fuller trip budget including lodging and food? See our Road Trip Cost Calculator.
Getting a Trip Budget You Can Trust from the Fuel Cost Calculator
A fuel cost calculator gives a clean number, but the road rarely matches the brochure. Build in a little realism before you set a budget.
- Use your own recent economy, not the official rating. Motorway speeds, heavy loads and roof racks all cut it.
- Take the distance from a mapping app for the actual route and add a margin for detours.
- Fuel prices vary between regions and are often highest at motorway services, so enter a price near the top of what you expect.
- Set the units carefully: miles with US gallons, or kilometres with litres. Mixing up US and imperial gallons skews the fuel cost calculator by about a fifth.
For a long trip, run the fuel cost calculator with a best-case and a worst-case economy figure; the gap between the two is a sensible contingency.
The Wikipedia article on fuel economy in automobiles explains why speed, load and weather change consumption, which helps you choose sensible inputs for the fuel cost calculator. Tolls, parking and charging are not part of what a fuel cost calculator estimates, so budget those separately.