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Journey cost

Trip fuel cost calculator

Estimate how much fuel a journey uses and what it costs. Choose one of eight market presets, then enter the consumption and price you actually pay. The result includes cost per mile and cost per 100 km.

UK: miles, MPG UK and pence per litre. US: miles, MPG US and dollars per US gallon. Europe, Switzerland and Australia: kilometres, L/100 km, local currency per litre. Japan, India and South Korea: kilometres, km/L, local currency per litre.

No national or live fuel price is assumed

Petrol, diesel and electricity prices vary by country, region, grade and station. This calculator uses only the price you enter. It cannot tell you the cheapest station near you.

Calculate the cost

Your inputs

Changing market resets the example values so the units cannot silently carry over.

mi

UK odometer distances are in miles.

Leave unticked for a one-way estimate.

MPG UK
p/litre

Use pence per litre: 145 means £1.45 per litre.

ExampleThese starting values are illustrative, not current prices. Replace them with the price and consumption you actually have.

Estimated result

Trip fuel estimate

Estimated fuel cost

£13.18

100 mi of driving (one way).

Fuel used

9.09 L

≈ 2 imperial gal

Cost per mile

£0.132

Cost per km

£0.082

Cost per 100 km

£8.19

Fuel only. Tolls, parking, ferry fares, maintenance and driving-style effects are not included. The price you enter is the only price used.

How the calculation works

United Kingdom

litres = miles ÷ MPG (UK) × 4.54609
cost = litres × (pence/litre ÷ 100)

The pump price is in pence per litre, while economy is usually quoted in imperial MPG. The conversion bridges those two conventions.

United States

US gallons = miles ÷ MPG (US)
cost = US gallons × dollars/gallon

US fuel is sold by the US gallon. A US gallon is 3.785411784 litres, not the imperial gallon used for UK MPG.

Europe / Switzerland / Australia

litres = km × (L/100 km) ÷ 100
cost = litres × local currency/litre

These markets normally quote litres per 100 kilometres. Cost per 100 km is therefore consumption multiplied by the price per litre.

Japan / India / South Korea

litres = km ÷ (km/L)
cost = litres × local currency/litre

These markets usually quote fuel economy in kilometres per litre, so litres used is distance divided by km/L rather than multiplied by litres per 100 km.

Cost per mile is total cost divided by miles. Cost per kilometre is total cost divided by kilometres. Both are shown so a UK or US result can still be compared with a metric one.

Worked examples

Illustrative inputs only. These are not current market prices.

UK example

100 miles · 50 MPG UK · 145 p/l

£13.18

9.09 litres · £0.132/mile

US example

300 miles · 30 MPG US · $3.50/gal

US$35.00

10 US gallons · US$0.117/mile

EU example

500 km · 6.5 L/100 km · €1.75/l

€56.88

32.5 litres · €11.38/100 km

What changes the real number

Driving style and speed

Published consumption figures come from a test cycle. Motorway speeds, cold starts, air conditioning, roof boxes and heavy loads can all change real consumption.

Fuel grade and type

Petrol, diesel, premium grades and regional blends can have different prices and consumption. The calculator does not assume one national price or grade.

Distance basis

A one-way route and a round trip are different. Tick the round-trip box when the return leg matters; the calculator doubles the distance rather than guessing.

What is excluded

Tolls, vignettes, ferries, parking, congestion charges, maintenance and depreciation are not part of a fuel-only estimate. Some of these need verified official data and are not published yet.

Questions

How do you calculate gas cost for a trip?
Divide the trip distance by the vehicle’s fuel economy to get the fuel used, then multiply by the price per unit. In the US: gallons = miles ÷ MPG, and cost = gallons × dollars per gallon. In the UK: litres = miles ÷ MPG UK × 4.54609, and cost = litres × pounds per litre.
How much does it cost to fill a car?
A full-tank cost is tank capacity multiplied by the price per litre or gallon. This calculator estimates fuel used for a journey, not a fill-up. To estimate a fill-up, enter your tank capacity as the quantity and multiply by the price.
Is it worth driving further for cheaper fuel?
Compare the saving on the fuel you need with the cost of the extra distance. A detour only pays if the price difference multiplied by the litres bought is greater than the extra distance divided by your MPG and multiplied by the price. For a small fill, a large detour rarely pays. This page does not provide live station prices.
Why does the UK use litres but MPG?
UK fuel is sold in litres, while vehicle economy has historically been quoted in miles per imperial gallon. The two conventions coexist. This calculator explicitly converts between them; it does not assume that a pence-per-litre price can be multiplied directly by MPG.
Can I use this for diesel?
Yes. Enter the diesel consumption and the diesel price you pay. The arithmetic is the same, but diesel and petrol prices can differ. The result is still a fuel-only estimate.

Official price sources

We do not reproduce these prices because they change and may not match your local station. Use them to check the market context, then enter your own price above.

Page last reviewed: . Formulas are covered by automated tests. Prices are inputs, not live data.

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