⛽ Fuel Cost Calculator
Work out how much fuel a road trip will use and what it will cost – then split the bill between everyone in the car.
Quick answer: Fuel cost = distance ÷ mpg × price per gallon. A 250-mile trip in a car that does 30 mpg uses 8.33 gallons; at $3.50 a gallon that is $29.17.
Updated · Free · No sign-up · Works on any device
Fuel Cost Calculator inputs
Result
Total fuel cost
$29.17
250 miles
| Fuel needed | 8.33 US gal · 31.55 L |
| Total cost | $29.17 |
- Cost per 100 miles
- $11.67
- Distance
- 250 miles
Trip cost at different fuel prices
| Price | Total | Fuel |
|---|---|---|
| $2.80/gal | $23.33 | 31.5 L |
| $3.15/gal | $26.25 | 31.5 L |
| $3.50/gal | $29.17 | 31.5 L |
| $3.85/gal | $32.08 | 31.5 L |
| $4.20/gal | $35.00 | 31.5 L |
How to calculate fuel cost
Fuel cost depends on three things: how far you drive, how efficient the vehicle is, and what fuel costs. Work out the fuel needed first, then multiply by the price.
Gallons = miles ÷ mpg · Litres = km × L/100 km ÷ 100 · Cost = fuel × price
Worked example
A 250-mile drive in a car rated at 30 mpg uses 250 ÷ 30 = 8.33 gallons. At $3.50 per gallon the trip costs 8.33 × 3.50 = $29.17. Make it a round trip and the cost doubles to $58.33; split between two people that is $29.17 each.
Fuel economy conversions
| US mpg | UK mpg | L/100 km | km/L |
|---|---|---|---|
| 20 | 24.0 | 11.8 | 8.5 |
| 25 | 30.0 | 9.4 | 10.6 |
| 30 | 36.0 | 7.8 | 12.8 |
| 40 | 48.0 | 5.9 | 17.0 |
| 50 | 60.0 | 4.7 | 21.3 |
The calculator handles all four economy units and prices per US gallon, UK gallon or litre, converting between them automatically.
Ways to cut fuel costs
- Keep tyres at the recommended pressure – under-inflation can cost several percent in economy.
- Drive smoothly; hard acceleration and braking waste fuel.
- Slow down: economy typically falls quickly above 50–60 mph (80–100 km/h).
- Remove roof racks and unnecessary weight when not needed.
- Compare fuel prices along your route with a fuel-price app before you set off.
Electric and hybrid vehicles
For a hybrid, simply enter its combined mpg or L/100 km. For an electric car, use the electricity cost calculator instead: multiply the trip distance by the car's consumption in kWh per mile or per 100 km, then by your charging price per kWh.
Frequently asked questions
How do I calculate gas cost for a trip?
Divide the distance by your car's miles per gallon to get gallons used, then multiply by the price per gallon. With L/100 km, multiply the distance in km by the rating and divide by 100 to get litres.
How do I convert mpg to L/100 km?
Divide 235.21 by the US mpg figure. 30 mpg is about 7.8 L/100 km. For UK (imperial) mpg, divide 282.48 by the mpg figure instead.
Should I use the official fuel economy figure?
Official ratings are measured under test conditions. Real-world economy is often 10–20% worse, especially at highway speeds above 65 mph, with a roof box or in cold weather.
How should passengers split fuel costs?
The fairest simple method is to divide the total fuel cost evenly between everyone travelling, including the driver. Some groups also share tolls and parking the same way.