Fuel and trip formulas
Fuel used = distance / MPG for US-style MPG. Fuel used in liters = distance(km) x L/100 km / 100. Trip fuel cost = fuel used x fuel price.
EV and charging formulas
Charging energy need = battery capacity x state-of-charge change / charging efficiency. A 60 kWh battery charged from 20% to 80% needs about 36 kWh before charging losses.
Tire and engine examples
Tire diameter from a 225/50R17 tire is wheel diameter plus two sidewalls. Sidewall height is 225 mm x 0.50 = 112.5 mm. Engine displacement depends on bore, stroke and cylinder count.
Common mistakes
- Comparing MPG and L/100 km as if both move in the same direction.
- Ignoring charging losses for EV cost.
- Using tire width in millimeters with wheel diameter in inches without conversion.
- Using highway efficiency for city driving.
Use the calculators
- Fuel Cost Calculator
- Fuel Efficiency Converter
- EV Charging Cost Calculator
- Tire Diameter Calculator
- Engine Displacement Calculator
FAQ
Why are MPG and L/100 km easy to mix up?
MPG increases as efficiency improves, while L/100 km decreases as efficiency improves. They move in opposite directions.
Should EV charging calculators include losses?
For cost planning, yes. Wall energy can be higher than battery energy because charging is not perfectly efficient.
References
- U.S. Department of Energy: Fuel Economy - Official US fuel economy resource, accessed 2026-05-15.
Last reviewed: 2026-05-15.