Fuel Consumption Calculator
This fuel consumption calculator works out your consumption from the fuel you filled and the distance you drove. With 45.2 litres over 650 kilometres you get 6.95 l/100 km, that is 14.38 km per litre, and at 1.80 per litre a cost of 12.52 per 100 km.
Example: What do you want to calculate: Consumption from a fill-up and distance · Fuel filled 45.2 l · Distance since the last full tank 650 km · Price per litre (optional) 1.8 → Result: Consumption: 6.95 l/100 km. Source: Wikipedia – Fuel economy in automobiles: l/100 km, km/l and mpg. Updated: .
How it is calculated
How to calculate fuel consumption – the full-tank method
The most accurate way is the full-tank method: fill up, note the odometer, drive, then fill up again to the same level. The litres added and the distance driven give your consumption: litres ÷ kilometres × 100 = l/100 km. With 45.2 l over 650 km that is 6.95 l/100 km.
Other figures
- km per litre: kilometres ÷ litres, here 14.38 km/l.
- mpg: 235.215 ÷ l/100 km for the US gallon, 282.481 ÷ l/100 km for the imperial gallon.
- Cost: consumption × price per litre gives the cost per 100 km, divided by 100 the cost per kilometre.
Fuel needed for a trip
The second mode works the other way round: at 6.5 l/100 km and 400 km you need 6.5 × 400 ÷ 100 = 26 litres, which at 1.80 per litre costs 46.80.
Limits
A single fill-up varies with driving style, temperature, tyre pressure and where the pump cuts off. For a reliable figure, average several fill-ups. The trip computer can differ from real consumption; the fill-up method measures what actually went through the nozzle.
Frequently asked questions
How do you calculate fuel consumption?
Divide the litres filled by the kilometres driven and multiply by 100. 45.2 l over 650 km is 6.95 l/100 km.
How do I work out fuel consumption per 100 km?
Use litres ÷ kilometres × 100. The calculator also shows km per litre, mpg and the cost.
How much fuel do I need for a trip?
Multiply consumption in l/100 km by the kilometres and divide by 100. For 400 km at 6.5 l/100 km that is 26 litres.
How accurate is the full-tank method?
It beats the trip computer if you always fill until the pump clicks off. Averaging several fill-ups smooths out outliers.
Why does my consumption differ from the official figure?
Official figures come from test cycles. Driving style, route, load and weather change real-world consumption a lot.
Sources and legal basis
As of: · Editorial policy
Related tools
- mpg to l/100km converterConvert mpg to l/100km and back, plus km/l: US and UK gallon, step-by-step formula, a comparison chart and the range you get from a full tank.
- Gas cost calculatorGas cost calculator for road trips: enter mpg, miles and gas price to get the total fuel cost, cost per person, gallons used and cost per mile. Metric too.
- EV charging cost calculatorWork out what charging your electric car costs at home and at a public charger – from battery size, state of charge, charging losses and your price per kWh.
- Speed, Distance and Time CalculatorSpeed distance time calculator: find speed from distance and time, or distance and time from the other two. Results in mph, km/h, m/s and knots with the steps.
- Stopping distance calculatorCalculate thinking, braking and total stopping distance in mph or km/h from reaction time and road conditions (dry, wet, snow, ice) – with the physics formula.
- kg to lbs converterConvert kg to lbs and back: 1 kg = 2.2046 lb. Shows pounds and ounces, stone and pounds, grams, tons and a kg to lbs chart – exact to the legal definition.
- Mileage Reimbursement CalculatorMileage reimbursement calculator: enter miles driven and a rate per mile – pre-filled with the 2026 IRS business rate of 76 cents – and get the amount.
- 2 stroke oil mix calculator2 stroke oil mix calculator: oil for 25:1, 32:1, 40:1, 50:1 or 100:1 per gallon or litre of fuel, with a table of typical fill-ups, percentages and fl oz. Free.
- m/s to mph converterm/s to mph: multiply by 2.2369, so 10 m/s = 22.3694 mph. Convert meters per second to miles per hour or back, with km/h, knots and a speed chart.