Fuel Trip Calculator
Estimate the fuel and cost of a journey in metric or imperial, split between passengers.
Work Out What a Journey Costs in Fuel
Fuel efficiency is quoted three incompatible ways around the world. Britain and America use miles per gallon — with different gallons. Most of Europe uses litres per 100 kilometres, where lower is better. Parts of Asia and South America use kilometres per litre. Converting between them by hand invites mistakes.
This calculator works in either of the two most common systems — kilometres with L/100 km, or miles with MPG — converts as needed, works out what the trip costs, and divides it between however many people are in the car.
Key features
- Both systems — kilometres, litres and L/100 km, or miles, gallons and MPG. Switching converts what you have already typed rather than relabelling it, which is where these tools usually go wrong.
- Both equivalents shown — your economy in L/100 km and in US MPG side by side, since the two are reciprocals and nobody converts them in their head.
- Cost per distance — per kilometre or mile, and per 100, which is the figure worth knowing for expense claims.
- Split between passengers — the per-person figure for shared trips and lift-sharing.
- Fuel volume needed — how much you will actually burn, which is what matters for range planning.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Fuel Trip Calculator
- Pick your units
Kilometres and L/100 km, or miles and MPG. Everything else follows from that choice. - Enter the distance
The whole journey. Double it yourself if you are coming back. - Enter economy and price
Your car’s real observed figure, and the pump price. Real-world economy runs around 15% worse than the official number. - Split it if sharing
Set the number of people to get the per-person cost.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Calculators |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
Why is my real economy worse than the official figure?
Official figures come from standardised laboratory cycles that involve gentle acceleration, no hills, no cold starts and no air conditioning. Real driving includes all four. Fifteen percent worse is typical; short urban journeys can be far worse than that.
How do I convert MPG to L/100 km?
Divide 235.21 by the US MPG figure, or 282.48 by the imperial one. The relationship is inverse, not linear, which is why it cannot be a simple multiplication — and why switching units here converts rather than just relabelling.
Does this cover an electric vehicle?
Not directly. Enter your consumption in kWh per 100 km as if it were L/100km and your electricity price as the fuel price — the arithmetic is identical, only the units differ.
Is a US gallon the same as an imperial one?
No. An imperial gallon is 4.546 litres against the US 3.785, about 20% larger, so a car rated 40 MPG imperial is roughly 33 MPG US for the same real efficiency. Check which one your figure is quoted in before you trust the result.