Fuel Economy & Fuel Cost Calculators
Calculate MPG, fuel consumption, gas mileage, fuel costs, and trip fuel expenses with free, easy-to-use calculators. Convert between US MPG, UK MPG, km/L, and L/100km.
Calculate MPG, km/L, L/100km, and fuel costs with real-time updates
Equivalent to 38.21 UK Imperial MPG
MPG = Distance (mi) ÷ Fuel (gal)|L/100km = (Liters ÷ km) × 100Popular Fuel Calculators
Dedicated calculation suites tailored to every automotive fuel measurement scenario
Fuel Economy Calculator
Calculate vehicle efficiency across US MPG, UK Imperial MPG, km/L, and L/100km from distance and fuel pumped.
Fuel Consumption Calculator
Determine metric fuel consumption in liters per 100km (L/100km) and kilometers per liter from distance and fuel volume.
MPG Calculator
Calculate miles per gallon directly, distinguish between US and UK gallons, and convert instantly between all units.
Gas Mileage Calculator
Track your car’s real-world gas mileage and cost per mile from trip odometer readings and gas pump receipts.
Fuel Cost Calculator
Calculate total gasoline expense, fuel needed, and cost per mile based on distance, vehicle MPG, and gas price.
Trip Fuel Cost Calculator
Plan road trip gasoline budgets, toggle one-way or round-trip journeys, and split travel expenses equitably among passengers.
How Fuel Economy Calculations Work
Engineered for high precision with unrounded intermediate physical constants
Every formula strictly adheres to official physical conversions from the NIST SP 811 Metric Guide: 1 mi = 1.609344 km, 1 US gal = 3.785411784 L, and 1 UK gal = 4.54609 L.
Calculations execute instantly in your browser with zero network latency, zero tracking scripts, and complete privacy.
All outputs seamlessly compute imperial and metric counterparts simultaneously, making international comparison effortless.
Understanding the 4 global standards of automotive fuel measurement recognized by FuelEconomy.gov (DOE)
Standard in the United States. Based on the 3.785-liter US liquid gallon. Higher numbers mean better fuel efficiency.
Standard in the UK. Because the UK gallon is 4.546 liters (20% larger than US), UK MPG numbers are 20% higher than US MPG for the same car.
Standard across Europe, Canada, and Australia. Measures fuel consumption. Lower numbers indicate superior fuel economy.
Popular in Japan, India, Brazil, and Italy. Measures distance per liter. Higher numbers indicate better fuel economy.
Fuel Economy Conversions
Quick reference lookup table for common passenger vehicle efficiency ratings
| US MPG | UK Imperial MPG | km/L | L/100km | Typical Vehicle Class |
|---|---|---|---|---|
| 20.0 MPG | 24.02 MPG | 8.50 km/L | 11.76 L/100km | Full-size Pickup / V8 SUV |
| 25.0 MPG | 30.02 MPG | 10.63 km/L | 9.41 L/100km | Mid-size Crossover / Minivan |
| 30.0 MPG | 36.03 MPG | 12.75 km/L | 7.84 L/100km | Compact SUV / Sedan |
| 35.0 MPG | 42.03 MPG | 14.88 km/L | 6.72 L/100km | Compact Hatchback / Sedan |
| 40.0 MPG | 48.04 MPG | 17.01 km/L | 5.88 L/100km | Hybrid Crossover / Diesel Sedan |
| 50.0 MPG | 60.05 MPG | 21.26 km/L | 4.70 L/100km | Compact Hybrid Sedan |
Step-by-step mathematical formulas, measurement techniques, and practical explanations
Fuel consumption measures the volume of fuel a vehicle uses to travel a specific distance. In the metric system, it is commonly expressed in liters per 100 kilometers (L/100km) or kilometers per liter (km/L). In the United States, it is expressed as miles per gallon (MPG).
Gas mileage measures how many miles a vehicle travels per gallon of gasoline consumed. In the United States, gas mileage is expressed as miles per gallon (MPG). To calculate your gas mileage, divide the miles driven by the US gallons of fuel used (MPG = Miles Driven ÷ Gallons Used). Because a UK Imperial gallon is approximately 20% larger than a US gallon, UK Imperial MPG figures are numerically higher for the exact same vehicle.
Fuel expenses represent one of the largest ongoing operational costs of vehicle ownership. Calculating your cost per mile and trip costs enables accurate tax deductions, road trip cost sharing, and smart commuter budgeting.
Miles Per Gallon (MPG) is the standard measurement of vehicle fuel economy in the United States and the United Kingdom. Here is the exact math behind MPG calculations and unit comparisons.
L/100km and MPG are inverse metrics. One measures fuel consumption (volume per distance), while the other measures fuel economy (distance per volume). This difference creates a well-documented cognitive bias known as the MPG Illusion.
When reading British automotive publications like Top Gear or Autocar, you may notice vehicles achieving seemingly incredible fuel economy. This difference is caused by the physical volume of the British Imperial gallon.