Fuel Cost Calculator
Free fuel cost calculator — work out how much a trip will cost in fuel from distance (km), consumption (km/L), and price per litre. Runs in your browser.
Type the trip distance, your car’s consumption (km/L), and the current fuel price. The calculator returns the total fuel cost for the trip and the number of litres you’ll burn.
The formula
litres needed = distance (km) ÷ consumption (km/L)
cost = litres × price-per-litre
A 500 km trip in a car doing 12 km/L burns 500 ÷ 12 ≈ 41.67 L. At $1.80
per litre that’s $75.
Converting your numbers
The calculator wants km/L. If your dashboard shows other units:
- L/100 km: km/L = 100 ÷ (L/100 km). Example: 8 L/100 km → 12.5 km/L.
- US mpg: km/L ≈ mpg × 0.4251. Example: 25 mpg US ≈ 10.6 km/L.
- UK Imperial mpg: km/L ≈ mpg × 0.3540. (Imperial gallons are larger.)
Real-world vs. rated consumption
Manufacturer-rated MPG / consumption is typically 10–15% optimistic versus real-world. Use your dashboard’s recent-average display if you have it; that’s the most accurate input. For a long trip with mixed roads, the overall average usually beats either purely-highway or purely-city tests.
What’s not in this calculator
Just fuel. The full cost of a trip also includes:
- Tolls and parking,
- Wear and tear (depreciation, tyres, brakes — IRS uses ~$0.67/mile in the US),
- Maintenance amortized over distance,
- Time. (At minimum-wage rates, an hour of driving “costs” $15+.)
For a “should I drive or fly” comparison, fuel cost alone usually under-counts. For “how much do I owe my carpool buddy”, fuel alone is usually the fair number.
Worked examples
-
500 km trip at 12 km/L and $1.80/L
Trip cost: $75.00 — 41.67 L of fuel for 500 km.
-
1,200 km road trip at 14 km/L and $1.95/L
Trip cost: $167.14 — 85.71 L of fuel for 1,200 km.
Frequently asked questions
How is fuel cost calculated?
Litres needed = distance ÷ consumption (km/L). Cost = litres × price-per-litre. So a 500 km trip in a car doing 12 km/L needs 500 ÷ 12 ≈ 41.67 L; at $1.80/L that's about $75.
My car's consumption is in litres per 100 km — how do I convert?
km/L = 100 ÷ (L/100 km). So 8 L/100 km is 100 ÷ 8 = 12.5 km/L. Conversely L/100 km = 100 ÷ (km/L). They're inverses.
My car is in miles per gallon (mpg) — how do I plug it in?
Convert mpg to km/L: 1 mpg (US) ≈ 0.4251 km/L; 1 mpg (UK Imperial) ≈ 0.3540 km/L. A 25 mpg US car ≈ 10.6 km/L. Or use km/L directly — most car displays can switch units.
What about hills, traffic, AC, headwind?
All affect real-world consumption. The number on the dashboard usually shows your *recent* average, which is the best input. Manufacturer-rated consumption tends to be 10–15% optimistic vs real-world.
Tolls, parking, depreciation?
Not in this calculator. Total cost of a trip also includes those, plus wear and tear and (for some people) the time-value of the hours spent driving. This one is **just** fuel.