EV Charging Cost Calculator
This charge costs $7.00.
| Figure | Value |
|---|---|
| Charge added 20% → 80% | 60% of the pack |
| Energy into the battery | 45 kWh |
| Lost to heat 10% of the draw | 5 kWh |
| Energy from the grid what you pay for | 50 kWh |
| Cost at $0.14/kWh | $7.00 |
| Range added | 158 miles |
| Cost per mile | $0.04 |
| Full 0–100% charge | $11.67 |
| Cost per year 12000 miles | $533 |
The meter reads more than the battery receives. Energy is lost to heat in the onboard charger and the pack itself, so charging is 85–90% efficient on AC at home and lower on DC fast charging. Most EV cost calculators ignore this and understate the bill by 10–15%. Charging from 20% to 80% is the normal pattern rather than 0–100%: lithium packs charge much more slowly above 80%, and habitually filling to 100% shortens pack life, which is why manufacturers recommend an 80% daily limit. The gap between charging types is the real story — the same charge that costs a few dollars at home overnight can cost three or four times as much on a DC fast charger, so an EV's running cost depends far more on where you charge than on which car you bought. Real efficiency also drops considerably in cold weather, often by 20–30%.
Calculate what an EV charge actually costs — including the energy lost to heat — per session, per mile, and per year.
How to use this calculator
- Enter your battery capacity in kWh — the usable figure, which is slightly below the headline number on most cars.
- Set the starting and target charge. 20% to 80% is the normal daily pattern.
- Pick a charging type to preset a realistic rate and efficiency, or set them yourself.
- Enter your car's miles per kWh and your annual mileage for cost per mile and per year.
The formula
Energy to battery = Capacity × (Target % − Start %) · Energy from grid = Energy to battery ÷ Efficiency
Cost = Grid energy × Rate · Cost per mile = Cost ÷ (Battery energy × Miles per kWh)
Worked example — a 75 kWh pack from 20% to 80%
Home Level 2 charging at 14¢/kWh, 90% efficient, car doing 3.5 mi/kWh.
- Into the battery: 75 × 60% = 45 kWh
- From the grid: 45 ÷ 0.90 = 50 kWh — 5 kWh lost to heat
- Cost: 50 × $0.14 = $7.00
- Range added: 45 × 3.5 = 158 miles
- Cost per mile: 4.4¢
For comparison, a 25 MPG petrol car at $3.50 a gallon costs 14¢ a mile — more than three times as much. Now run the same charge on a DC fast charger at 48¢/kWh, where efficiency is also lower, and it becomes about $25 and 16¢ a mile — no cheaper than petrol at all.
Where you charge decides everything
| Charging | Typical rate | Cost per mile at 3.5 mi/kWh | 158-mile charge |
|---|---|---|---|
| Home, off-peak | 9¢/kWh | ≈ 2.9¢ | $4.50 |
| Home, standard | 14¢/kWh | ≈ 4.4¢ | $7.00 |
| Public Level 2 | 30¢/kWh | ≈ 9.7¢ | $15.30 |
| DC fast charging | 48¢/kWh | ≈ 16.1¢ | $25.40 |
That is a fivefold spread on identical electricity in an identical car. An EV owner who charges at home overnight is running at a fraction of petrol cost; one who relies on DC fast chargers may be paying more than a petrol car would. Anyone comparing an EV against a petrol car should be honest about which of those they will actually be.
The losses nobody counts
Electricity does not arrive in the battery unchanged. Some becomes heat in the onboard charger converting AC to DC, some in the cabling, and some in the battery's own internal resistance. The utility meter records everything that left the grid; the car reports what reached the pack. The difference is 10–15% on AC home charging and more on DC fast charging, where thermal management is working hard.
This calculator includes it, which is why a 45 kWh charge shows as 50 kWh billed. It is not a large error individually, but across a year it is the difference between a fuel budget that is right and one that is consistently 12% short.
Why 80% is the normal target
Lithium-ion cells charge quickly up to roughly 80% state of charge and then slow markedly as the battery management system tapers current to protect the pack. On a DC fast charger, going from 80% to 100% can take as long as going from 20% to 80% — which is why road-trip advice is to stop more often for shorter charges rather than filling to the top.
There is also a longevity argument. Sitting at a high state of charge accelerates degradation, so most manufacturers recommend an 80% daily limit and reserve full charges for long journeys. Many cars let you set this limit in software and simply stop there.
What this does not include
- Charger installation, typically $500–$2,000 for a home Level 2 unit including electrical work.
- Network subscription fees on some public charging providers, and idle fees for leaving a car plugged in after it finishes.
- Demand charges or time-of-use tiers that some utilities apply, which can make the marginal rate different from the average one.
- Battery preconditioning, which uses energy before a fast charge but makes the charge faster.
How we calculate this
Energy into the battery is capacity × the change in state of charge. Energy drawn from the grid is that figure divided by the charging efficiency, because losses occur between the meter and the pack — this is the step most calculators omit, and it understates the bill by 10–15% when they do. Cost is grid energy × the rate. Range added is battery energy × miles per kWh, and cost per mile follows from the two. Efficiency defaults reflect typical figures: about 90% for AC home charging, lower for DC fast charging where more is lost to heat and thermal management.
Sources
Frequently asked questions
How much does it cost to charge an electric car?
At home, charging a 75 kWh pack from 20% to 80% draws about 50 kWh from the grid once losses are counted, which at 14 cents per kWh is about $7 for roughly 158 miles — around 4.4 cents a mile. The same charge on a DC fast charger at 48 cents per kWh would cost about $24.
Why does charging draw more energy than the battery holds?
Because charging is not perfectly efficient. Energy is lost as heat in the onboard charger, the cabling, and the battery itself, so the meter always records more than reaches the pack. Home AC charging runs about 85–90% efficient, and DC fast charging somewhat less. Most EV cost calculators ignore this and understate the bill by 10–15%.
How much does it cost to charge an EV at home versus a public charger?
Home charging typically runs 10–16 cents per kWh, off-peak rates lower still. Public Level 2 is often around 30 cents, and DC fast charging 40–60. That means the same electricity can cost three or four times more depending on where you plug in — an EV's running cost depends far more on where you charge than on which car you bought.
Why charge to 80% instead of 100%?
Two reasons. Charging slows dramatically above 80% as the battery management system tapers the current, so the last 20% can take as long as the first 60. And routinely charging to 100% accelerates battery degradation, which is why most manufacturers recommend an 80% daily limit and saving full charges for long trips.
How many miles per kWh does an electric car get?
Most current EVs manage 3 to 4 miles per kWh in mixed driving. Efficient small cars can exceed 4; large electric trucks and SUVs may be 2 or below. Some manufacturers quote the inverse instead — kWh per 100 miles — where lower is better, in the same way L/100km inverts MPG.
Does cold weather affect EV charging costs?
Considerably. Efficiency commonly drops 20–30% in winter, partly because cabin heating draws directly from the pack with no waste engine heat to use, and partly because cold batteries are less efficient at both charging and discharging. Expect meaningfully more kWh per mile between roughly November and March.
How long does it take to charge an electric car?
A Level 2 home charger typically adds 20–30 miles of range per hour, so an overnight session covers almost any daily driving. DC fast charging can take a pack from 20% to 80% in 20–40 minutes depending on the car and the charger. A standard household outlet adds only 3–5 miles an hour, which is fine as a top-up and impractical as a primary method.
Is it cheaper to run an EV than a petrol car?
On home charging, almost always and usually by a wide margin — often 4 to 6 cents a mile against 12 to 18. On exclusively public fast charging the gap narrows sharply and can disappear entirely against an efficient hybrid. Where you charge is the deciding variable.