PetrolCalculator

Fuel calculator

How Much Petrol Should I Put In My Car?

Estimate petrol required for a journey.

Estimate petrol required

Enter journey details to estimate petrol required.

What your result means

This estimates petrol required from journey distance and UK MPG. The result is an estimate: real-world fuel use can change with traffic, speed, load and weather.

Worked example

Using 100 miles, 45 UK MPG and 142p per litre:

Journey miles
100
UK gallons required
2.22
Petrol required
10.1 litres
Estimated fuel cost
£14.35

The same model also applies an optional return journey before calculating fuel use.

Formula

UK gallons=Journey milesUK MPG\text{UK gallons}=\frac{\text{Journey miles}}{\text{UK MPG}}
Litres=UK gallons×4.54609\text{Litres}=\text{UK gallons}\times4.54609

Helpful questions

Does a return journey double the estimate?

Yes. With the same MPG and price, selecting a return journey doubles the entered distance, fuel required and estimated fuel cost.

Why can actual fuel use differ?

Traffic, speed, driving style, load, weather and road conditions affect real-world MPG. Use the MPG Calculator to measure a real figure.

Should I add a safety margin?

A modest margin can be sensible when fuel availability or driving conditions are uncertain. Do not rely on an estimate to run the tank close to empty.

Related calculators