Tankful
The fuel cost of a trip comes down to one formula:
For example, the Warsaw – Berlin drive is 571 km. A car using 7 l/100 km burns 40 litres of petrol on it, which at the route's weighted average price of €1.94/l comes to €77.35 one way.
Step by step
- Check the distance of the route you'll actually drive – in your navigation app or the calculator. The shortest route isn't always the fastest, and the difference can be tens of kilometres.
- Use your real consumption, ideally from the trip computer on a motorway drive. City and motorway figures differ a lot.
- Multiply the distance by the consumption and divide by 100 – that's the number of litres.
- Multiply the litres by the price per litre. On a trip through several countries, cost each section at that country's price.
- For a return trip double the result; if several people share the car, divide by the number of people.
If you work in miles and mpg: litres = miles × 1.609 ÷ 100 × (282.5 ÷ UK mpg). Or skip the maths and let the calculator switch to miles and gallons.
Examples with current prices
One-way cost at typical consumption: petrol 7 l, diesel 6 l, LPG 9 l per 100 km.
| Route | km | Petrol (95) 7 l | Diesel 6 l | LPG 9 l |
|---|---|---|---|---|
| Warsaw – Berlin | 571 km | €77.35 | €72.74 | €41.60 |
| Wrocław – Prague | 287 km | €37.59 | €35.68 | €21.50 |
| Kraków – Vienna | 465 km | €61.34 | €58.67 | €34.75 |
| Kraków – Budapest | 523 km | €65.77 | €61.96 | €41.27 |
| Warsaw – Amsterdam | 1,195 km | €181 | €165 | €102 |
| Warsaw – Paris | 1,591 km | €239 | €221 | €140 |
On international routes the price is weighted by the kilometres in each country – so Warsaw – Paris, for example, is costed largely at German prices.
A trip through several countries
If a route crosses several countries, a single price gives the wrong answer. It's more accurate to split the route into sections: kilometres in each country × consumption ÷ 100 × the price in that country, then add them up. For Warsaw – Amsterdam, 1,195 km across three countries, the kilometre-weighted petrol price is €2.17/l.
The Tankful calculator does this for you: it works out how many kilometres of the route fall in each country and takes the current average price from each of them.
The most common mistakes
- Using the brochure consumption instead of the real one. Manufacturers quote a test result – on the motorway you'll usually use 10–30% more.
- Forgetting the way back or driving around at the destination.
- One price for a whole international trip, although fuel next door can be 30 cents a litre dearer or cheaper.
- Counting a ferry as road. A car on a ferry burns no fuel – the calculator leaves ferry sections out, but it's easy to forget when you do it by hand.
Don't want to do it by hand? The Tankful calculator plans the route and works out the cost for petrol, diesel, LPG and EVs with current prices.