Gas Mileage Calculator
Calculate your vehicle fuel efficiency in MPG or L/100km and estimate fuel costs for trips.
A gas mileage calculator measures your vehicle's fuel efficiency in MPG or L/100km so you can track consumption and compare costs.
Examples
Road trip efficiency
Metric example
Frequently Asked Questions
What is a good MPG?
How do MPG and L/100km relate?
Quick Tips
- •Fill your tank completely, reset your trip odometer, and refill completely for the most accurate measurement.
- •MPG varies with driving conditions: highway typically yields 20-30% better MPG than city driving.
- •Tire pressure, speed, and AC usage significantly affect fuel efficiency.
A gas mileage calculator measures your vehicle's fuel efficiency in MPG or L/100km so you can track consumption and compare costs.
How to Use This Calculator
Select your unit system, enter the distance traveled, fuel used, and fuel price. The calculator computes fuel efficiency (MPG or L/100km) and cost per distance unit.
Understanding the Formula
MPG = Miles / Gallons. Cost per mile = (Gallons x Price) / Miles. Metric: L/100km = (Liters / Kilometers) x 100. Conversion: 1 gallon = 3.785 liters, 1 mile = 1.609 km.
Examples
Road trip efficiency
300 miles on 12 gallons at $3.50/gal: MPG = 25.0, Total cost = $42.00, Cost/mile = $0.14.
Metric example
500 km on 40 liters: 12.5 km/L = 8.0 L/100km. This equals about 29.4 MPG.
Frequently Asked Questions
What is a good MPG?
The average new car in the US gets about 25-30 MPG combined. Hybrids typically achieve 40-60 MPG, while EVs equivalent can exceed 100 MPGe.
How do MPG and L/100km relate?
They are inversely related: 235.214 / MPG = L/100km. A car getting 30 MPG uses about 7.8 L/100km. Lower L/100km is better, while higher MPG is better.
Assumptions & Limitations
- Accuracy depends on completely filling the tank at both the start and end of measurement.
- MPG varies significantly between city and highway driving; this calculates a combined average.
- Fuel price is assumed constant for the entire calculation period.