How to use this calculator
- Choose US, UK, or Metric so distance, economy, currency, and fuel-volume units agree.
- Enter the distance for one leg and select Round trip when the return leg is similar.
- Enter a realistic economy figure for the vehicle and expected conditions.
- Enter the price you expect to pay; no live price is inserted.
- Calculate and review fuel used, total distance, fuel cost, and cost per mile or kilometre.
Formula and variables
US gallons used = trip miles ÷ US MPGMetric litres used = kilometres × L/100 km ÷ 100Fuel cost = fuel used × price per matching volume unitCost per distance = fuel cost ÷ total trip distance
What each input means
- Distance is supplied by you; the site does not look up routes.
- Fuel economy must use the selected US MPG, Imperial MPG, or L/100 km unit.
- Fuel price must match the displayed US gallon, Imperial gallon, or litre unit.
- Trip type determines whether the entered one-way distance is used once or doubled.
Choosing the right units
US and Imperial gallons are different sizes. Presets synchronize all related units. Price fields clear after a preset or currency change because FuelTripCost has no exchange-rate source.
Worked examples
100 miles
At 25 US MPG, 100 miles uses 4 US gallons. At $3.50 per gallon, fuel costs $14.00 and the fuel cost per mile is $0.14.
250 and 500 miles
At the same 25 US MPG and $3.50 price, 250 miles uses 10 gallons and costs $35.00; 500 miles uses 20 gallons and costs $70.00.
Round trip
A 125-mile one-way drive selected as a round trip becomes 250 miles. At 25 US MPG and $3.50 per gallon, it uses 10 gallons and costs $35.00.
Metric example
A 180 km drive at 6.5 L/100 km uses 11.7 litres. At an example input of €1.80 per litre, fuel costs €21.06.
| Economy | Fuel | Cost | Cost/mile | Saving vs 20 MPG |
|---|---|---|---|---|
| 20 MPG | 25 gal | $87.50 | $0.175 | — |
| 25 MPG | 20 gal | $70.00 | $0.140 | $17.50 |
| 30 MPG | 16.67 gal | $58.33 | $0.117 | $29.17 |
| 35 MPG | 14.29 gal | $50.00 | $0.100 | $37.50 |
Real-world factors
- Traffic, idling, terrain, towing, roof loads, weather, tire pressure, and driving style can change real consumption.
- A measured economy figure from similar driving may be more representative than a rating from different conditions.
- A single fuel price is a planning average, not a forecast for every stop.
When to use it
- Budget a known drive.
- Compare one-way and return expense.
- Test how economy or fuel price changes cost.
Common mistakes
- Entering a return distance and also selecting Round trip.
- Combining US MPG with a price per Imperial gallon or litre.
- Treating fuel-only cost as the full cost of owning a vehicle.
Limits of the estimate
The tool does not know traffic, route changes, elevation, idling, vehicle condition, current pump prices, or exchange rates. Maintenance, depreciation, insurance, taxes, tolls, and parking are excluded.
Questions about this calculator
How is trip fuel cost calculated?
Divide distance by MPG to find gallons, then multiply by price per gallon. With L/100 km, multiply kilometres by L/100 km and divide by 100, then multiply litres by price per litre.
Should I enter one-way or total distance?
Enter one-way distance and use Trip type. If you already have the complete out-and-back distance, leave the tool set to One way.
Why is fuel price not filled automatically?
Prices vary by place and time, and this site has no live price feed. Enter the price you expect to pay.