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Trip Fuel Cost Calculator - Litres, Cost per km and Split Between Passengers

Enter the distance, your vehicle's efficiency and the fuel price, and the calculator shows the litres needed, the total cost, the cost per kilometre, each person's share and, if you like, a month's fuel.

Maintained by Hirantha Sandaruwan Lakshan. Updated 28 October 2026.

About this tool

It works with km per litre or litres per 100 km, and it can double the distance for a return trip. The Ceylon Petroleum Corporation's pump prices from 1 October 2026 are one tap away (Petrol 92 Rs. 414, Auto diesel Rs. 392), or type the price you pay. Nothing you type leaves your device.

How it works

Fuel needed is the distance driven divided by km per litre. The cost is litres times the price per litre, and the cost per kilometre is the cost divided by the distance driven. A return trip doubles the distance. An optional extra allowance multiplies the litres, so a 10% allowance on 10 litres is 11 litres.

Km per litre and litres per 100 km are the same measure written two ways: km per litre = 100 divided by (litres per 100 km). So 12.5 km per litre is 8 litres per 100 km, and 5 litres per 100 km is 20 km per litre. A higher km per litre is better, and a lower litres per 100 km is better.

The price buttons hold the Ceylon Petroleum Corporation's retail prices from its revision effective 1 October 2026: Petrol 92 Octane Rs. 414, Petrol 95 Octane Euro 4 Rs. 475, Auto diesel Rs. 392 and Super diesel Rs. 528 a litre. The page does not fetch prices, and the CPC revises them about once a month, so check the date and type the price you pay if it has changed. The Rs. 300 and Rs. 280 in the first examples are round numbers chosen to make the sums easy.

Money is rounded to the cent only at the end. Each person's share is the rounded total divided by the number of people, so when the total does not divide evenly the shares can add up to a cent more or less than the total. Include the driver in the number of people if the driver should pay a share.

Worked examples

120 km each way, four people (example price Rs. 300 a litre)

A return trip is 240 km. At 12 km per litre that is 240 / 12 = 20 litres. At an example price of Rs. 300 a litre the cost is 20 x 300 = Rs. 6,000, which is Rs. 25.00 per kilometre and Rs. 1,500 each for four people. The Rs. 300 is made up to show the sum.

Litres per 100 km (example price Rs. 280 a litre)

A car rated at 8.5 litres per 100 km on a 150 km one-way trip uses 150 x 8.5 / 100 = 12.75 litres. At an example price of Rs. 280 a litre that is 12.75 x 280 = Rs. 3,570, or Rs. 23.80 per kilometre.

Two vehicles on the same trip (example price Rs. 300 a litre)

For 100 km one way, a vehicle doing 15 km per litre uses 6.67 litres and costs Rs. 2,000. One doing 10 km per litre uses 10 litres and costs Rs. 3,000, so the thirstier vehicle costs Rs. 1,000 more for the same 100 km at that example price.

A month of driving on Petrol 92 (CPC price from 1 October 2026)

1,000 km a month at 12 km per litre is 83.33 litres. At the CPC's Rs. 414 a litre for Petrol 92 that is Rs. 34,500 a month, or Rs. 34.50 a kilometre.

Frequently asked questions

How do I calculate the fuel cost of a trip?

Divide the distance by your vehicle's km per litre to get the litres, then multiply the litres by the price per litre. For 240 km at 12 km per litre that is 20 litres, and at an example price of Rs. 300 a litre it costs Rs. 6,000.

How do I convert km per litre to litres per 100 km?

Divide 100 by the number. 12.5 km per litre is 100 / 12.5 = 8 litres per 100 km. The same division works the other way: 100 / 8 = 12.5 km per litre.

Which fuel price should I enter?

The price per litre you pay at the pump for your type of fuel. The buttons fill in the CPC's prices from 1 October 2026 (Petrol 92 Rs. 414, Petrol 95 Rs. 475, Auto diesel Rs. 392, Super diesel Rs. 528); if the price has changed since, type the new one. The page does not fetch prices.

Why is my real fuel use different from the result?

A manual's figure and your own driving can differ because of traffic, hills, load, air conditioning, speed and tyre pressure. For a better number, fill the tank, reset the trip meter, drive normally, refill, and divide the kilometres by the litres you added. Use the extra allowance for slow or hilly trips.

Are tolls, parking and vehicle wear included?

No. The result is fuel only. Tolls, parking, tyres, servicing and depreciation are extra costs of a trip.

How does the cost split work?

The total is divided equally by the number of people you enter, to the cent. Include the driver in that number if the driver should pay a share too. Leave it blank for one person.

Does it work for motorbikes and three-wheelers?

Yes. Enter the km per litre or litres per 100 km of that vehicle. Motorbikes and three-wheelers usually cover more kilometres per litre than cars, so use a figure for your own vehicle.

Is my data stored or sent anywhere?

No. The sums run in your browser and nothing you type is sent or saved.

Updated Oct 28, 2026