Fuel Cost Calculator
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Enter a trip distance, your vehicle's fuel efficiency and the price of fuel to work out how much fuel you will use and what the journey will cost. Switch between MPG and L/100km units, all calculated on your device.
How trip fuel and cost are calculated
The calculator works out fuel used from your distance and efficiency, then multiplies by the fuel price. In imperial units it divides the distance in miles by your miles-per-gallon figure to get gallons used. In metric units it multiplies the distance in kilometres by your L/100km rating and divides by one hundred to get litres used.
Once the amount of fuel is known, the total cost is simply fuel used multiplied by the price per gallon or litre. The tool also divides the total cost by distance to show a cost-per-mile or cost-per-kilometre figure, which is handy for comparing routes, vehicles or reimbursement rates.
Understanding MPG and L/100km
These two efficiency measures run in opposite directions, which trips people up. With miles per gallon, a higher number means better efficiency because you travel further on the same fuel. With litres per 100 kilometres, a lower number is better because you burn less fuel over the same distance.
The unit toggle lets you enter whichever figure your vehicle reports. Modern dashboards and manufacturer specs vary by region, so pick the system that matches your data rather than converting by hand. The results adjust automatically to the units you choose.
- MPG: higher is better, common in the US and UK
- L/100km: lower is better, common across Europe
- Price is entered per gallon for MPG or per litre for L/100km
Getting the most from the tool
For accurate results, use a realistic efficiency figure. Official ratings are measured in ideal conditions, so real-world driving with traffic, hills, air conditioning and a full load usually consumes more fuel. If you track your own consumption, use that number for the best estimate.
The calculator is ideal for budgeting road trips, comparing the running cost of two vehicles, splitting fuel costs with passengers, or estimating business mileage. Because it updates instantly, you can try different fuel prices to see how rising or falling pump prices change the cost of a regular commute.
Frequently asked questions
Which units should I choose?
Pick the system your vehicle uses. Choose miles and MPG with a price per gallon, or kilometres and L/100km with a price per litre. The input labels change to match your selection.
How is cost per mile or kilometre worked out?
It divides the total trip cost by the distance travelled, giving a per-unit figure that is useful for comparing routes or claiming mileage.
Should I enter one-way or round-trip distance?
Enter whichever you want to price. Use the round-trip distance to include the return leg, or the one-way distance for a single journey.
Why does my real cost differ from the estimate?
Real driving conditions, traffic, terrain, load and driving style all affect consumption. Using your own measured efficiency gives a closer estimate than the official rating.
Can I convert between MPG and L/100km here?
The tool does not convert between the two directly, but you can enter whichever figure you have and get accurate costs in that unit system.
Is anything stored or shared?
No. All numbers stay in your browser and the calculation runs entirely on your device.
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