# Fuel Cost Calculator

URL: https://speedycalculator.com/calculators/everyday-life/fuel-cost/
Last updated: 2026-10-25

> The fuel cost calculator works out the fuel needed and cost of a trip from the distance, fuel economy (mpg, km/L or L/100 km) and fuel price, split per person, plus the cost per mile or kilometre.

## Inputs

- Distance (mi, km, m, nmi)
- Round trip (double the distance)
- Fuel economy given as
- Fuel economy (mpg (US), mpg (UK), km/L)
- Fuel consumption (L/100 km)
- Fuel price (/US gal, /L, /UK gal)
- People sharing the cost

## Results

- Fuel needed
- Trip fuel cost
- Cost per person
- Cost per distance
- CO₂ emitted (petrol)

## Formula

```
Fuel used = distance ÷ fuel economy (or distance × L/100 km ÷ 100)
Trip cost = fuel used × fuel price
Cost per person = trip cost ÷ people
```

## Explanation

Fuel is the biggest running cost of most trips, and it is easy to estimate once you know your car's real-world fuel economy. Driving at a steady 50–60 mph, keeping tyres inflated and removing roof boxes can improve economy by 10–20%.

### How to use the Fuel Cost Calculator

- **Distance**
- **Round trip (double the distance)**
- **Fuel economy given as**
- **Fuel economy**
- **Fuel consumption**
- **Fuel price**
- **People sharing the cost**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the distance, choose whether it is a round trip, give the fuel economy in your preferred unit, the fuel price and the number of people sharing the cost.

### Tips

- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field's menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.

### Common mistakes to avoid

- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.

### Inputs explained

FieldWhat to enterDistanceUnits: mi, km, m, nmiRound trip (double the distance)Choose one: No, YesFuel economy given asChoose one: Distance per volume (mpg, km/L), Litres per 100 kmFuel economyUnits: mpg (US), mpg (UK), km/LFuel consumptionIn L/100 kmFuel priceUnits: /US gal, /L, /UK galPeople sharing the costA number

### What each result means

- **Trip fuel cost** = [Fuel needed]×[Fuel price]
- **Cost per person** = [Trip fuel cost]÷[People sharing the cost]
- **CO₂ emitted (petrol)** = [Fuel needed]×2347.697029306865

### Example values

How the main result changes when **Distance** changes and everything else stays at the example values above:

Distance (mi)Trip fuel cost12517.5187.526.2525035312.543.7537552.550070

## Worked example

Inputs — Distance: 250 mi; Round trip (double the distance): No; Fuel economy given as: Distance per volume (mpg, km/L); Fuel economy: 25 mpg (US); Fuel consumption: 8 L/100 km; Fuel price: $3.5 /US gal; People sharing the cost: 1.

Results — Fuel needed = 10 US gal; **Trip fuel cost = $35.00**; Cost per person = $35.00; Cost per distance = $0.140 /mi; CO₂ emitted (petrol) = 88.9 kg.

## FAQ

**How do I calculate fuel cost for a trip?**
Divide the distance by your mpg to get gallons, then multiply by the price per gallon. 250 miles at 25 mpg and $3.50/gal costs $35.

**How do I convert L/100 km to mpg?**
US mpg = 235.21 ÷ L/100 km; UK mpg = 282.48 ÷ L/100 km.

**Does speed affect fuel economy?**
Yes – above about 55–60 mph aerodynamic drag rises quickly; driving at 75 instead of 60 mph can use 20% more fuel.

**What formula does the Fuel Cost Calculator use?**
Fuel used = distance ÷ fuel economy (or distance × L/100 km ÷ 100).


## Sources

- [U.S. DOE – fueleconomy.gov driving tips](https://www.fueleconomy.gov/)