Fuel Cost Calculator

When to use it

Fuel is the most visible cost of a journey and the easiest to underestimate, because the figure on the dashboard is an average and the pump price changes weekly. This page multiplies distance, consumption and price into the cost of one trip, and doubles the distance when you choose the round trip.

Use it to split a holiday drive, to compare driving with a train ticket, or to see what a change of commute does to a monthly budget. The result is fuel only: tolls, parking, wear and depreciation are separate costs.

How the maths works

Litres = distance × consumption ÷ 100. Cost = litres × price per litre. The round-trip option doubles the distance before the calculation, and the yearly line multiplies the one-way cost by 104, which is two trips a week for a year.

Cost per kilometre is consumption ÷ 100 × price, a figure that stays constant whatever the distance. That is why it is the number worth remembering: at 6.2 L/100 km and 1.85 per litre, every kilometre costs about 0.11.

A worked example

450 km at 6.2 L/100 km, with fuel at 1.85 per litre.

1. Fuel: 450 × 6.2 = 2,790, divided by 100 = 27.9 litres.
2. Cost: 27.9 × 1.85 = 51.62.
3. Round trip: 900 km and 55.8 litres, so 103.23.
4. Twice a week for a year: 51.62 × 104 = 5,367.96.

The yearly figure is the one that changes decisions: a daily commute that costs 10 a day is more than 2,500 a year.

Trip costs at a glance

The last two rows are the same journey in an efficient and a thirsty car: a difference of 25 on a single trip, and about 2,600 over a year of twice-weekly drives.

Common mistakes

• Entering miles per gallon. This page wants litres per 100 km; convert first with the fuel economy converter.
• Using the brochure figure. Cold starts, air conditioning, load and traffic all push real consumption above the official number.
• Forgetting the return leg. Half of all trip estimates are wrong for this reason alone.
• Confusing the price unit. A price per gallon must be converted to a price per litre before it goes in the field.

Keep exploring

• Fuel Economy Converter — convert between litres per 100 km, km/L and US mpg.
• Unit Price Comparison — compare two filling stations per litre.
• Electricity Cost Calculator — the same cost-per-use thinking for the home.