Petrol Amount Calculator
Petrol amount calculator works out Fuel cost and Total trip cost from Distance, Distance unit and Fuel economy. The default figures on this page give fuel needed of 34.0957; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
1 step
- Fuel needed = 300 mi / economy = 34.0957 litres.
Its 9 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
2 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the petrol amount calculator calculates
Computes the fuel needed and its cost for a journey from distance, fuel economy and fuel price, in either US or metric units, and can solve instead for the fuel volume alone, the economy achieved, the distance a tank covers, or the fuel price a known spend implies.
How to use this petrol amount calculator
Enter Distance, Distance unit, Fuel economy and Economy unit. Fuel cost updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Fuel cost, Total trip cost and Cost per person.
The method follows US EPA fuel economy definitions and the mpg to L/100km relationship and NIST Special Publication 811 for the exact gallon, mile and litre definitions.
What you can compare
Change one input at a time to see how it affects Fuel cost, Total trip cost and Cost per person. The inputs you can vary are Distance, Distance unit, Fuel economy, Economy unit and Price is per.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How to calculate the amount of petrol?
Computes the fuel needed and its cost for a journey from distance, fuel economy and fuel price, in either US or metric units, and can solve instead for the fuel volume alone, the economy achieved. Open “How this is worked out” beside the result to see each step for your own figures.
How much is 1 km of petrol?
On the figures this page opens with — distance 300 and fuel economy 30 — the fuel needed is 34.0957. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the petrol amount calculator?
You need Distance, Distance unit, Fuel economy, Economy unit and Price is per. The page opens with default figures that give fuel needed of 34.0957, so you can see the scale before entering your own.
What does this petrol amount calculator show?
It shows Fuel cost, Total trip cost, Cost per person, Fuel needed, Distance travelled, Cost per mile or km, Economy in US mpg and Economy in L/100km, with the working and any warnings for your entries.
Can I check how the petrol amount calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.