Quick answer: divide the distance by your car’s economy to get the fuel, then multiply by the price: 450 km ÷ 14 km/L = 32.1 litres, × 280 per litre = 9,000. With L/100 km, multiply instead: 450 × 7.1 ÷ 100 = 32 litres. For a round trip, double the distance.
Know your fuel economy
| Unit | Used in | Lower or higher is better? |
|---|---|---|
| km per litre (km/L) | Pakistan, India, much of Asia | Higher |
| litres per 100 km (L/100 km) | Europe, Australia, Canada | Lower |
| miles per gallon (US) | United States | Higher |
| miles per gallon (UK) | United Kingdom | Higher – a UK gallon is 20% bigger |
Conversions: L/100 km = 100 ÷ km/L (14 km/L ≈ 7.1 L/100 km). 1 US mpg = 0.425 km/L; 1 UK mpg = 0.354 km/L.
Use your real figure, not the brochure
Manufacturer figures are measured in ideal conditions. Real-world economy is often 10–25% worse, more with air-conditioning, heavy loads, roof racks and city traffic. The best number is your own: fill the tank, reset the trip meter, drive normally, refill and divide kilometres by litres.
Example trips
- Lahore → Islamabad and back (≈ 380 km each way, 14 km/L): about 54 litres.
- A 300-mile US road trip at 30 mpg and $3.50 a gallon: 10 gallons, $35.
- A London → Manchester drive (≈ 330 km) at 6 L/100 km: about 20 litres.
Splitting with friends? Set the number of people and everyone sees their share – tolls and parking can be added on top.
Splitting the trip with friends? The bill splitter in the tip calculator divides any total fairly, and the time calculator adds up driving time across several days.
How to calculate fuel cost for a trip
- Enter the distance. In km or miles. Tick round trip if you are coming back the same way.
- Enter your fuel economy. Choose the unit your car or country uses: km/L, L/100 km or MPG.
- Enter the fuel price. Per litre, or per gallon if you use MPG.
- Split the cost. Set the number of people sharing the ride to see each share.
Worked example: what better economy saves
1,000 km a month with fuel at 280 per litre:
| Car | Fuel used | Monthly cost | Yearly cost |
|---|---|---|---|
| 14 km/L | 71.4 L | 20,000 | 240,000 |
| 9 km/L | 111.1 L | 31,111 | 373,333 |
The more economical car saves about 11,000 a month at the same mileage – useful when comparing cars, or deciding whether a smaller car for daily commuting pays off.
Ways to use less fuel
- Keep tyres at the right pressure – under-inflated tyres raise consumption.
- Drive smoothly and stay around 80–90 km/h on highways.
- Remove roof racks and extra weight you don’t need.
- Combine short trips; a cold engine uses much more fuel.
Frequently asked questions
How do I calculate fuel cost?
Fuel needed = distance ÷ km per litre (or distance × L/100 km ÷ 100). Cost = fuel needed × price per litre.
How do I convert km/L to L/100 km?
Divide 100 by the km/L figure. 14 km/L is about 7.1 L/100 km.
What is the difference between US and UK MPG?
A UK (imperial) gallon is 4.546 litres and a US gallon 3.785 litres, so the same car shows a higher MPG in the UK.
Does it include tolls and parking?
No, only fuel. Add tolls and parking to the total yourself.
How do I find my car’s real fuel economy?
Fill up, reset the trip meter, drive normally, fill up again and divide the distance by the litres added.
Can I use it for electric cars?
Not directly. For an EV multiply distance by kWh per km and by your electricity price.
How do I compare petrol and CNG or diesel costs?
Run the calculator once per fuel with that fuel’s economy and price, then compare the cost per km.
How much fuel does a 100 km trip use?
At 14 km/L about 7.1 litres; at 6 L/100 km exactly 6 litres. Enter your car’s figure for the exact amount.