Overview
What this calculator does
Estimate how much fuel a trip needs and what it will cost, from the distance, your vehicle's fuel economy, and the price of fuel. It works in MPG (US), L/100km, or km/L, handles round trips, and splits the cost between passengers for carpools.
The math
The formula
MPG (US)
fuel = distance ÷ MPG, then cost = fuel × price per gallon. For 300 miles at 30 MPG with $3.50 gas: 300 ÷ 30 = 10 gallons × $3.50 = $35.
L/100km (Europe)
fuel = (distance ÷ 100) × L/100km. For 500 km at 7 L/100km: 5 × 7 = 35 litres.
km/L (some Asian countries)
fuel = distance ÷ km/L. For 400 km at 15 km/L: 400 ÷ 15 = 26.7 litres.
Around the world
Understanding fuel economy units
| Used in | Better is | |
|---|---|---|
| MPG (miles per gallon) | US, UK (imperial gallon) | Higher |
| L/100km (litres per 100 km) | Most of Europe, Canada | Lower |
| km/L (kilometres per litre) | India, Japan, others | Higher |
US vs UK gallons differ
Save at the pump
Tips to cut fuel cost
- Drive smoothly — hard acceleration and braking waste fuel
- Keep to steady highway speeds; fuel economy drops sharply above ~70 mph (110 km/h)
- Keep tires properly inflated — under-inflation increases rolling resistance
- Remove roof racks and extra weight when not needed
- Combine errands into one trip; a warm engine is more efficient
- Carpool and split the cost — the per-person feature shows the savings
The full cost of driving
What's not included
This calculator covers fuel only. The true cost of a trip also includes tolls, parking, and a share of maintenance, tires, and depreciation. Many organizations estimate the all-in cost of driving at a fixed rate per mile or km that's several times the fuel cost alone. For budgeting a big trip, add those extras.
Behind the scenes
Privacy and how it runs
Runs in your browser
Common questions
How much will gas cost for my road trip?
Enter the total distance, your car's MPG (or L/100km), and the fuel price. The calculator shows the fuel needed and the total cost. Toggle round trip to double the distance automatically.
What fuel economy figure should I use?
Your real-world average, which is usually a little worse than the official rating — especially in city driving. Many cars display average fuel economy on the dashboard. If unsure, use the manufacturer's combined figure as a starting point.
How do I split fuel cost with friends?
Set the "split between" number to the number of people sharing the ride. The per-person amount divides the total fuel cost evenly — a fair way to share a carpool or road trip.
Does highway or city driving matter?
Yes, a lot. Cars are usually more efficient on the highway at steady speeds than in stop-and-go city traffic. If your trip is mostly one or the other, use the matching fuel-economy figure for a more accurate estimate.
How do electric vehicles compare?
EVs are measured in miles or km per kWh and charged at electricity prices, so this fuel calculator doesn't apply directly. EV "fuel" cost is typically much lower per mile than gasoline, though it varies with local electricity rates.
Related calculators
Travel and money tools that pair with the fuel calculator.
Last reviewed: · Methodology based on US building code standards, contractor pricing surveys, and manufacturer specifications.