EV vs Gas Calculator
Compare running costs of an electric car against petrol, and find the break-even.
Please note: Estimates for planning only. Real fuel economy, depreciation, insurance and lease terms vary widely by vehicle, region and driving style. Confirm figures against a dealer quote or your own records before relying on them.
What the EV vs Gas Calculator does
The comparison rests on cost per mile for energy. An EV’s advantage comes from electricity being cheaper per unit of useful energy and electric drivetrains being far more efficient — but a purchase premium has to be recovered from those savings, and how quickly depends almost entirely on annual mileage and charging rates.
Formula
EV kWh per year = Distance ÷ 100 × kWh/100km ÷ Charging efficiencyEV cost = kWh × Electricity ratePetrol cost = Distance ÷ 100 × L/100km × Price per litreBreak-even = Purchase premium ÷ Annual saving
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Distance driven per year | number | Yes | Accepts more than 0. |
| Distance unit | one of 2 options | Yes | — |
| EV efficiency | number | Yes | Accepts more than 0. |
| EV efficiency measured in | one of 4 options | Yes | — |
| Electricity rate per kWh | selected currency | Yes | Accepts 0 or more. |
| Charging efficiency | % | Yes | — |
| Petrol car economy | number | Yes | Accepts more than 0. |
| Fuel economy measured in | one of 4 options | Yes | — |
| Fuel price per unit | selected currency | Yes | Accepts more than 0. |
| Fuel priced per | one of 3 options | Yes | — |
| Extra purchase cost of the EV | selected currency | Optional | Accepts 0 or more. |
| Annual maintenance saving on the EV | selected currency | Optional | Accepts 0 or more. |
| Years to project | number | Yes | Accepts 1 or more, up to 20. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Distance unit and EV efficiency measured in.
- Enter Distance driven per year, EV efficiency, Electricity rate per kWh and Charging efficiency and 3 more.
- Optionally add Extra purchase cost of the EV and Annual maintenance saving on the EV.
- Select Calculate.
Worked example
12,000 miles a year: an EV at 3.5 mi/kWh charging at $0.15, against a 30 mpg car with $3.50 fuel, an $8,000 premium and $400 of maintenance saved.
- Distance
- 12,000 mi
- EV
- 3.5 mi/kWh
- Rate
- $0.15
- Petrol
- 30 mpg
- Fuel
- $3.50
EV energy costs $571 a year against $1,400 of petrol. With maintenance that is $1,229 saved, breaking even on the premium in 6.5 years.
Reading the result
- "Equivalent petrol price for parity" gives a single benchmark to remember — if gas prices ever fell to that figure, the EV's running-cost edge would vanish.
- The "break-even mileage" table shows payback shrinking non-linearly with distance — doubling annual miles roughly halves the payback period, since the purchase premium is fixed while the saving scales with distance.
Assumptions and limitations
- Electricity rate and fuel price are both held constant for the entire projection — a multi-year projection at today's prices doesn't account for either commodity moving over that horizon.
- "Maintenance saving" is a single flat annual figure — the notes mention it's real but also that tyres often wear faster on heavier EVs, a cost that could partially offset it.
Common mistakes
- Assuming the EV's running-cost advantage applies regardless of where you charge — the notes state public rapid charging can erase the advantage entirely.
- Treating a "never" break-even result as meaning the EV is a bad choice overall — this tool covers running costs and purchase premium only, not other reasons for choosing one.
Frequently asked questions
Does an EV always work out cheaper to run?
On energy, almost always with home charging. Whether it is cheaper overall depends on the purchase premium and how many miles you cover each year.
Why include charging efficiency?
Because you pay for what the meter records, not what reaches the battery. Ignoring the roughly 10% loss understates EV running costs.