Gas vs EV Cost Calculator
The EV costs less per mile.
| Gas | EV | |
|---|---|---|
| Cost per mile | $0.14 | $0.04 |
| Per year | $1,680 | $480 |
| Over 8 years | $13,440 | $3,840 |
| Fuel saved over 8 years | $9,600 | |
| Less the EV price premium | − $5,000 | |
| Net over 8 years | $4,600 | |
| Break-even on the premium | 4.2 years | |
Cost per mile is the honest comparison, because MPG and miles-per-kWh are not directly comparable units. The variable that moves the answer most is where the EV charges: home overnight at an off-peak rate is dramatically cheaper than DC fast charging, often by a factor of four, and an EV driven mostly on public fast chargers can genuinely cost more per mile than a petrol car. This compares fuel only — it does not include the differences in maintenance (EVs have no oil changes, no exhaust, and far less brake wear thanks to regeneration, but tyres wear faster), insurance (usually higher for an EV), depreciation, or any purchase tax credit, which can more than erase the price premium. Cold weather cuts EV efficiency by 20–30%, so a winter-heavy climate shifts the comparison meaningfully.
Compare a petrol car against an electric one on cost per mile and per year, and find how long a price premium takes to pay back.
How to use this calculator
- Enter the petrol car's MPG and your local fuel price.
- Enter the EV's miles per kWh and the electricity rate you would actually pay — home, off-peak, or public. This is the input that decides the answer.
- Set your annual mileage.
- Enter the price premium — how much more the EV costs, net of any tax credit — and the number of years you want to compare.
The formula
Gas ¢/mile = Price per gallon ÷ MPG · EV ¢/mile = Price per kWh ÷ Miles per kWh
Annual saving = (Gas ¢/mile − EV ¢/mile) × Annual miles · Break-even years = Premium ÷ Annual saving
Worked example — 25 MPG against 3.5 mi/kWh
Petrol at $3.50/gal, home electricity at 14¢/kWh, 12,000 miles a year, a $5,000 price premium.
- Gas: 3.50 ÷ 25 = 14¢ per mile → $1,680 a year
- EV: 0.14 ÷ 3.5 = 4¢ per mile → $480 a year
- Annual saving: $1,200
- Break-even on the premium: 5,000 ÷ 1,200 = 4.2 years
- Over 8 years: $9,600 saved, $4,600 ahead after the premium
The variable that decides it
Change nothing except where the EV charges and the conclusion inverts:
| EV charging at | EV ¢/mile | Gas ¢/mile | Annual saving |
|---|---|---|---|
| Home off-peak, 9¢/kWh | 2.6¢ | 14¢ | $1,372 |
| Home standard, 14¢/kWh | 4.0¢ | 14¢ | $1,200 |
| Public Level 2, 30¢/kWh | 8.6¢ | 14¢ | $652 |
| DC fast, 48¢/kWh | 13.7¢ | 14¢ | $34 |
At home the EV saves over a thousand dollars a year. On exclusively DC fast charging the saving is essentially nothing — and against a 40 MPG hybrid rather than a 25 MPG car, the same fast-charging EV would cost more to run. Whether you can charge at home is the question to settle before anything else.
What this comparison leaves out
Fuel is one line of several, and the others do not all point the same way:
| Cost | Usually favours | Why |
|---|---|---|
| Fuel / electricity | EV, strongly | Cheaper energy and a far more efficient drivetrain |
| Routine maintenance | EV | No oil, no exhaust, no belts; regen spares the brakes |
| Tyres | Gas | EVs are heavier and torquier, so tyres wear faster |
| Insurance | Gas | Higher values and costlier repairs on EVs |
| Depreciation | Historically gas | EVs have fallen faster, though this is shifting |
| Purchase price | Gas, before credits | Tax credits can erase the gap where they apply |
For the complete picture, run both vehicles through the cost of ownership calculator, where depreciation — usually the largest cost of all — is included alongside everything else.
A note on price stability
Petrol prices are volatile in a way residential electricity is not. Fuel can swing 50% within a year on events entirely outside your control, while regulated electricity rates typically move slowly and predictably. That means the EV running cost you calculate today is more likely to still be roughly accurate in three years than the petrol figure is — worth something on its own, even before the arithmetic.
How we calculate this
Both vehicles are reduced to cost per mile, which is the only basis on which MPG and miles-per-kWh can be compared. Gas cost per mile is price per gallon ÷ MPG; EV cost per mile is price per kWh ÷ miles per kWh. Annual costs are those figures times annual mileage, and the saving is the difference. Break-even is the price premium divided by the annual saving, reported only when the EV both costs more up front and saves per mile — otherwise there is no break-even to find, and the calculator says so rather than printing a meaningless number.
Sources
Read more
Frequently asked questions
Is an electric car cheaper to run than a gas car?
On home charging, almost always. A 25 MPG petrol car at $3.50 a gallon costs 14 cents a mile; an EV doing 3.5 miles per kWh on 14-cent electricity costs 4 cents. Over 12,000 miles that is $1,680 against $480 — a saving of $1,200 a year. On exclusively public fast charging the gap narrows sharply and can vanish.
How do I compare MPG to miles per kWh?
You cannot directly — they measure different fuels. Convert both to cost per mile instead. Gas cost per mile is price per gallon divided by MPG; EV cost per mile is price per kWh divided by miles per kWh. That gives one number you can compare honestly, and it is what this calculator does.
How long does it take for an EV to pay off its higher price?
Divide the price premium by the annual fuel saving. A $5,000 premium against $1,200 a year of saved fuel breaks even in about 4.2 years. Tax credits shorten this considerably where they apply, and expensive public charging lengthens it — sometimes to never.
Does the comparison include maintenance?
No, this compares fuel only. Maintenance generally favours EVs: no oil changes, no exhaust system, no timing belts, and far less brake wear because regenerative braking does most of the slowing. Against that, EV tyres wear faster due to weight and torque, and insurance is usually higher. The net is normally still in the EV's favour but by less than fuel alone suggests.
What about the tax credit on an electric car?
Where available it can substantially or entirely erase the price premium, which changes the break-even calculation completely. Enter the premium net of any credit you will actually receive — eligibility depends on the vehicle, where it was built, battery sourcing, and your own income, and the rules change often.
Does cold weather change the comparison?
Yes, meaningfully. EV efficiency commonly drops 20–30% in winter because cabin heating draws from the battery and cold cells are less efficient. Petrol cars lose efficiency in the cold too, but less. In a winter-heavy climate, model the EV at a lower miles-per-kWh figure than its rating.
Are gas prices or electricity prices more volatile?
Petrol prices move far more. Residential electricity rates are typically regulated and change slowly, while fuel prices can swing 50% in a year. That predictability is part of the appeal of an EV — the running cost you calculate today is likely to still be roughly right in three years, which is much less true of petrol.
What if I can't charge at home?
Then run this calculator at public charging rates, and be honest about it. Relying on DC fast charging at 40–60 cents per kWh can put an EV's cost per mile at or above an efficient petrol car's. Home charging is the single biggest factor in whether an EV saves money, and it is worth resolving before buying rather than after.