MPG Calculator: True Cost Per Mile and the EV vs Gas Comparison

MPG (miles per gallon) is how your car reports efficiency. Cost per mile is what you actually pay to drive. The difference matters when comparing vehicles, evaluating whether an EV makes financial sense, or understanding the true cost of a commute.

Our  converts between MPG, L/100km, and cost per mile. This guide covers the calculation and the EV comparison.

Cost per mile formula

Cost per mile = Fuel price per gallon / MPG

MPG	$3.00/gal	$3.50/gal	$4.00/gal
20 mpg	$0.150	$0.175	$0.200
25 mpg	$0.120	$0.140	$0.160
30 mpg	$0.100	$0.117	$0.133
35 mpg	$0.086	$0.100	$0.114
40 mpg	$0.075	$0.088	$0.100
50 mpg (hybrid)	$0.060	$0.070	$0.080

Annual fuel cost

Annual fuel cost = (Miles/year / MPG) x Price per gallon

Example: 15,000 miles/year, 28 MPG, $3.50/gallon:

Cost = (15,000 / 28) x $3.50 = 535.7 x $3.50 = $1,875/year

EV cost per mile

EVs use electricity measured in kilowatt-hours (kWh). Their efficiency is expressed in miles per kWh.

EV cost per mile = Electricity price ($/kWh) / Miles per kWh

Vehicle	Miles per kWh
Tesla Model 3	4.1
Tesla Model Y	3.5-4.0
Chevy Bolt	3.5
F-150 Lightning	2.2

Direct comparison: 30 MPG gas vs Tesla Model 3

Gas at $3.50/gallon: $3.50 / 30 = $0.117/mile

EV home charging at $0.13/kWh: $0.13 / 4.0 = $0.033/mile

EV is 72% cheaper per mile at home charging rates.

At 15,000 miles/year: Gas costs $1,750/year. EV costs $495/year. Savings: $1,255/year.

Public DC fast charging changes the math

Public fast charging runs $0.25-0.50/kWh. At $0.35/kWh on a 3.5 mi/kWh EV: $0.35 / 3.5 = $0.10/mile — similar to a 35 MPG gas car at $3.50/gallon. EVs are most economical for drivers who charge primarily at home. The savings largely evaporate for apartment dwellers who depend on public charging.

Fuel economy comparison: L/100km to MPG

MPG to L/100km: 235.21 / MPG

L/100km to MPG: 235.21 / (L/100km)

30 MPG = 7.84 L/100km. 6.5 L/100km = 36.2 MPG.

Calculate fuel costs, annual spending, and EV vs gas comparisons with the .