Fuel Economy Calculator
Calculate actual MPG, km/L, or L/100km from odometer readings and fuel receipts.
Track fuel economy across multiple fill-ups to spot efficiency trends.
Fuel economy measures how efficiently a vehicle converts fuel into distance traveled. There are two common metrics: MPG (miles per gallon, used in the US) and L/100km (liters per 100 kilometers, used in most of the world). Annual fuel cost depends on both fuel economy and how many miles/km you drive per year.
MPG formula: MPG = Miles Driven ÷ Gallons Used
L/100km formula: L/100km = (Liters Used ÷ Kilometers Driven) × 100
Converting between the two: L/100km = 235.21 ÷ MPG
Annual fuel cost formula: Annual Cost = (Miles Driven per Year ÷ MPG) × Price per Gallon
Or in metric: Annual Cost = (km/Year ÷ 100) × L/100km × Price per Liter
Where:
- Miles Driven per Year — US average is approximately 13,500 miles
- MPG — combined city/highway fuel economy rating
- Price per Gallon — varies by region and fuel grade; US average $3.20–$4.50 for regular
Fuel economy benchmarks:
- Economy cars (Civic, Corolla): 32–40 MPG combined
- Midsize sedans: 28–35 MPG
- SUVs and crossovers: 22–30 MPG
- Full-size trucks: 16–22 MPG
- Hybrid vehicles: 45–60 MPG
- Electric vehicles: equivalent 90–130 MPGe
Worked example: Driver travels 12,000 miles/year in an SUV rated at 24 MPG. Gas price: $3.80/gallon.
Annual fuel cost = (12,000 ÷ 24) × $3.80 = 500 gallons × $3.80 = $1,900/year
If they switch to a hybrid at 50 MPG: Annual fuel cost = (12,000 ÷ 50) × $3.80 = 240 gallons × $3.80 = $912/year Annual savings = $988 — the hybrid pays back its premium in approximately 5–7 years.