Fuel Cost Calculator
Calculate fuel needed and trip cost from distance, mpg or L/100km, and price per gallon.
Compare petrol and diesel and estimate annual driving fuel spend.
Annual fuel cost is one of the most overlooked factors when choosing or budgeting for a vehicle. Small differences in fuel efficiency compound into thousands of dollars over a car’s lifetime.
Annual fuel cost formula:
Annual Cost = (Annual Miles / MPG) × Price per Gallon
Or in metric:
Annual Cost = (Annual km / (100 / L/100km)) × Price per Liter
Simplified metric:
Annual Cost = Annual km × (L/100km / 100) × Fuel Price per Liter
Worked example (imperial):
Annual mileage: 15,000 miles. Fuel efficiency: 28 MPG. Fuel price: $3.50/gallon.
Annual Cost = (15,000 / 28) × $3.50 = 535.7 × $3.50 = $1,875/year
Worked example (metric):
Annual distance: 20,000 km. Efficiency: 8.5 L/100km. Price: $1.60/liter.
Annual Cost = 20,000 × (8.5 / 100) × $1.60 = 20,000 × 0.085 × 1.60 = $2,720/year
Cost comparison between two vehicles:
Annual Savings = (Miles/MPG_old × Price) − (Miles/MPG_new × Price)
Example: Switching from 22 MPG to 35 MPG at 15,000 miles/year, $3.50/gallon. Old: (15,000/22) × $3.50 = $2,386/year New: (15,000/35) × $3.50 = $1,500/year Annual savings: $886 — over 10 years, that is $8,860 in fuel alone.
Typical annual mileage benchmarks:
- US average: 13,500 miles (21,700 km)
- High commuter: 20,000–25,000 miles
- Low use / retiree: 5,000–8,000 miles