Fuel Cost Per Kilometre Calculator
Works out how much fuel costs you for every kilometre driven, from the fuel price and your vehicle’s consumption in litres per 100 km. It turns abstract fuel-economy figures into a real per-kilometre cost.
Last updated: May 2026
Compare with similar
About this calculator
Fuel cost per kilometre tells you what each kilometre of driving actually costs in fuel, which makes it easy to budget trips, compare vehicles, or decide whether a journey is worth driving. The formula is straightforward: fuel price (per litre) × consumption (litres per 100 km) ÷ 100. Dividing by 100 converts the "per 100 km" consumption figure into a per-kilometre amount. If fuel costs $1.80 per litre and your car uses 7 litres per 100 km, each kilometre costs 1.80 × 7 ÷ 100 = $0.126, or about 12.6 cents. Over a 400 km trip that is roughly $50 in fuel. The litres-per-100-km figure is the standard fuel-economy measure in most of the world (lower is better, unlike miles-per-gallon where higher is better). You can use your manufacturer’s combined-cycle rating, but real-world consumption is usually higher — city driving, air conditioning, roof racks, heavy loads, aggressive acceleration, and cold weather all push it up — so for honest budgeting use your own measured figure from a few fill-ups: litres added divided by kilometres driven, times 100. This calculator covers fuel only; the true cost per kilometre of running a car also includes depreciation, insurance, maintenance, tyres, and registration, which together often exceed the fuel cost. Still, fuel cost per kilometre is the most variable and trip-relevant component, and the easiest to act on by driving efficiently or choosing a more economical vehicle. To compare a petrol car with an electric one, compute the EV’s cost per kilometre from its kWh/100 km and your electricity price.
How to use
Example 1 — Family hatchback. Fuel is $1.80/L and the car averages 7 L/100km. Enter 1.80 and 7. Result: $0.126/km. Verify: 1.80 × 7 = 12.6; ÷ 100 = 0.126. ✓ A 300 km weekend trip costs about $37.80 in fuel. Example 2 — Thirsty SUV. Fuel is $2.10/L and the SUV uses 11 L/100km. Enter 2.10 and 11. Result: $0.231/km. Verify: 2.10 × 11 = 23.1; ÷ 100 = 0.231. ✓ Nearly double the hatchback, illustrating how consumption drives running costs.
Frequently asked questions
Where do I find my car’s fuel consumption figure?
The manufacturer publishes combined, urban, and highway figures in litres per 100 km in the owner’s manual and on the vehicle’s spec sheet or fuel-economy label. However, these official numbers are measured under idealised test conditions and most drivers see higher real-world consumption. For an accurate per-kilometre cost, measure your own: fill the tank, note the odometer, drive normally, refill, then divide the litres added by the kilometres travelled and multiply by 100. Averaging over several tanks smooths out variation. Using your real figure rather than the optimistic sticker value gives a far more honest cost estimate.
Why divide by 100 in the formula?
Because fuel consumption is expressed per 100 kilometres, not per single kilometre. If a car uses 7 litres to travel 100 km, then per kilometre it uses 7 ÷ 100 = 0.07 litres. Multiplying that by the price per litre gives the cost of one kilometre. Folding it into one step, cost per km = price × consumption ÷ 100. The division by 100 simply rescales the standard "L/100km" economy figure down to a single kilometre. If your consumption were already given per kilometre, you would skip the division, but virtually all economy ratings use the per-100-km convention.
Does this include all the costs of driving?
No — it covers fuel only. The complete cost of running a vehicle per kilometre also includes depreciation (the largest hidden cost for newer cars), insurance, registration, scheduled servicing, repairs, and tyres. Added together, these non-fuel costs frequently exceed the fuel cost itself, so the true cost per kilometre can be two to four times the fuel figure. Fuel cost per kilometre is still useful because it is the most trip-dependent and controllable component, and it is what changes when you take a longer route or choose a thirstier vehicle. For total ownership cost, build a separate budget that includes the fixed and maintenance items.
What mistakes do people make with fuel cost per km?
A frequent mistake is using the manufacturer’s optimistic combined figure rather than real-world consumption, which understates the cost. Another is forgetting that consumption rises significantly in city traffic, in cold weather, with a full load or roof rack, and with the air conditioning running — so a single highway-trip figure can be misleading for everyday driving. People also mix unit systems, such as entering miles-per-gallon economy into a litres-per-100-km field, which gives nonsense. Finally, some treat the fuel cost as the total running cost and forget depreciation, insurance, and maintenance, dramatically understating what the car really costs to operate.
When should I use a different approach?
If you drive an electric vehicle, this petrol/diesel formula does not apply directly — compute the EV’s cost per kilometre from its energy use (kWh per 100 km) and your electricity price per kWh instead, using the same divide-by-100 logic. If you are comparing the total economics of two cars, you need full cost-of-ownership figures including depreciation and maintenance, not just fuel. For fluctuating fuel prices, use an average price over your typical refuelling period rather than a single day’s pump price. And if your consumption varies widely between city and highway driving, calculate each separately rather than relying on one blended number.