Gas Mileage Calculator (MPG)
Calculate your vehicle's fuel economy (MPG) and fuel cost per mile. Track gas mileage over time and compare vehicles on real-world fuel costs.
⛽ Transportation📐 MPG = Miles Driven / Gallons Used
Miles driven
Gallons used to fill up
Gas price ($/gal)
Miles per day (optional)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Gas Mileage Calculator (MPG) | MPG = Miles Driven / Gallons Used | miles per gallon |
Step-by-Step Examples
Example 1
Fill-Up Calc
350 miles driven, 12.5 gallons used, $3.50/gal.
- MPG = 350/12.5 = 28 MPG
- Cost per mile = $3.50/28 = $0.125
- 35 mi/day x 365 x $0.125 = $1,597/year
✓ 28 MPG / $0.125/mile
Example 2
Truck Check
280 miles, 18 gals, $3.80.
- MPG = 280/18 = 15.6 MPG
- $3.80/15.6 = $0.244/mile
- Vs hybrid at 45 MPG: $0.084/mile - saves $584/year at 35 mi/day
✓ 15.6 MPG
Example 3
EV Compare
40 kWh used, 150 miles, $0.13/kWh.
- MPGe = 33.7 kWh/gallon equivalent
- 150 mi / 40 kWh = 3.75 mi/kWh = 126 MPGe
- Cost/mile = 40kWh x $0.13 / 150 mi = $0.035/mi
✓ 126 MPGe / $0.035/mile
Real-World Applications
Drivers
Track and optimize your vehicle's real-world fuel economy.
Car Buyers
Compare vehicles on real fuel cost per mile.
Budget Planning
Calculate annual fuel costs for budget planning.
Fleet Managers
Track fleet fuel efficiency and cost per mile.
Common Mistakes to Avoid
⚠️
Not filling the tank completely
Fill-to-full method requires starting with a full tank and filling to full again to get accurate gallons used.
⚠️
Ignoring driving style
Highway vs city driving can differ 30-40% in MPG. Short trips hurt MPG most; the engine never fully warms up.
⚠️
Not accounting for tire pressure
Under-inflated tires reduce MPG by 0.2% per PSI. At 10 PSI low: ~2% less fuel economy = $70/year on $3,500 fuel budget.
Frequently Asked Questions
What is good gas mileage? ▾
Under 20 MPG: poor (large trucks, SUVs). 20-30 MPG: average. 30-40 MPG: good. 40-50 MPG: excellent (hybrids). 50+ MPGe: plug-in hybrids and EVs.
How to improve gas mileage? ▾
Maintain proper tire pressure (+0.5% per PSI). Avoid jackrabbit acceleration and hard braking. Remove excess weight. Replace dirty air filter. Use cruise control on highways. Avoid idling.
MPG vs L/100km conversion? ▾
MPG to L/100km: divide 235.21 by MPG. 28 MPG = 235.21/28 = 8.4 L/100km. L/100km to MPG: 235.21/L100km. Lower L/100km is better; higher MPG is better.
How much does 1 MPG improve cost? ▾
At 35 mi/day, $3.50/gal, going from 28 to 29 MPG saves: 35x365 x ($3.50/28 - $3.50/29) = $58/year. Efficiency gains matter more at lower MPG (going from 10 to 11 MPG saves much more than 28 to 29).
What is MPGe? ▾
Miles Per Gallon equivalent for EVs and PHEVs. 33.7 kWh of electricity = energy equivalent of 1 gallon of gas. A car getting 3.35 mi/kWh has 112 MPGe. Used for apples-to-apples efficiency comparison.