How to calculate fuel cost
Fuel cost depends on three things: how far you're driving, how much fuel your vehicle uses, and the price of fuel. In metric: fuel used = distance ÷ 100 × (L/100km). In imperial: fuel used = distance ÷ mpg. Multiply by the fuel price to get the cost.
Fuel cost per 100 miles and per 100 km
What 100 miles or 100 km costs at common fuel economies and prices. Scale for any trip: a 250-mile drive costs 2.5 times the per-100 figure.
| Per 100 miles | $3.00/gal | $3.50/gal | $4.00/gal | $4.50/gal |
|---|---|---|---|---|
| 20 mpg | $15.00 | $17.50 | $20.00 | $22.50 |
| 25 mpg | $12.00 | $14.00 | $16.00 | $18.00 |
| 30 mpg | $10.00 | $11.67 | $13.33 | $15.00 |
| 35 mpg | $8.57 | $10.00 | $11.43 | $12.86 |
| 40 mpg | $7.50 | $8.75 | $10.00 | $11.25 |
| 50 mpg | $6.00 | $7.00 | $8.00 | $9.00 |
| Per 100 km | 1.50 / litre | 1.75 / litre | 2.00 / litre |
|---|---|---|---|
| 5 L/100 km | 7.50 | 8.75 | 10.00 |
| 6 L/100 km | 9.00 | 10.50 | 12.00 |
| 7 L/100 km | 10.50 | 12.25 | 14.00 |
| 8 L/100 km | 12.00 | 14.00 | 16.00 |
| 10 L/100 km | 15.00 | 17.50 | 20.00 |
| 12 L/100 km | 18.00 | 21.00 | 24.00 |
The per-100 km table is in your own currency — read 1.50 as €1.50, £1.50 or whatever your local price per litre is.
Ways to cut fuel costs
- Keep tyres properly inflated and remove roof racks when not needed
- Drive smoothly — hard acceleration and braking waste fuel
- Combine errands into one trip and stick to steady speeds
How much does it cost to drive 100 miles?
At 30 mpg and $3.50 a gallon, $11.67. The formula is miles ÷ mpg × price per gallon — find your own car's figure in the table above.
How do I calculate fuel cost for a trip?
Divide the distance by your fuel economy, then multiply by the fuel price. In miles: miles ÷ mpg × price per gallon. In kilometres: km ÷ 100 × L/100km × price per litre. A 400 km trip at 7 L/100 km and 1.80 a litre costs 400 ÷ 100 × 7 × 1.80 = 50.40.
What's a good fuel efficiency figure?
Modern cars often manage 5–8 L/100km (roughly 30–47 mpg). Check your car's trip computer or manual for its real-world figure.