Key takeaways
- Start with energy and price
- The basic EV charging-cost formula
- Example: charging from 20% to 80%
- Cost at home versus public charging
An EV charge costs the kWh you're billed for times your price per kWh. In the illustrative example below, charging a 60 kWh battery from 20% to 80% takes 40 kWh from the wall and costs $7.20 at $0.18 per kWh. Start with usable battery capacity, the charge range and your tariff, and apply charging losses only once, at the right billing point.
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Start with energy and price
Asking what it costs to charge an EV is like asking what it costs to fill a gas tank. The answer depends on how much energy you add and what your electricity provider or charging network charges for it.
You don't need to know the car's brand to estimate a charge. You need the battery capacity, how full it is before and after charging, and the electricity price. For a more realistic number, allow for charging losses too.
The basic EV charging-cost formula
Here's the basic formula:
Battery energy added (kWh) = usable battery capacity (kWh) × (target charge % − starting charge %) ÷ 100
Then:
Estimated wall energy (kWh) = battery energy added ÷ (charging efficiency % ÷ 100)
Estimated electricity cost = billed energy × price per kWh
Charging efficiency covers the energy that never reaches the battery. If you don't know yours, use an adjustable assumption and label it as one, rather than treating a single figure as universal.
The calculator takes percentage inputs such as 20 and 80. If your tariff bills energy drawn from the wall or grid, use wall energy after losses. If billing is explicitly based on energy added to the battery, use battery energy instead. Ask the provider where it measures, because that decides which figure you're charged for.
Example: charging from 20% to 80%
Hypothetical example: every price, battery figure and efficiency assumption below is illustrative.
Take an EV with a 60 kWh usable battery, charging from 20% to 80%, an illustrative 90% charging efficiency, and electricity at $0.18 per kWh.
- Battery energy added: 60 × (0.80 − 0.20) = 36 kWh.
- Energy purchased after assumed losses: 36 ÷ 0.90 = 40 kWh.
- Charging cost: 40 × $0.18 = $7.20.
Read the result alongside your tariff
That isn't a quoted price or a real-world average. A charger with a session fee, time-based billing, taxes, or a variable rate can cost more, and charging speed can change during a session.
The EV Charging Cost Calculator lets you swap in your own battery size, target charge, efficiency, and local rate.
Run the numbers before you decide
Plug in your own figures from a written offer.
EV charging cost calculator: what a full charge costs Gas vs electric car cost calculator: which is cheaper?Cost at home versus public charging
At home, you might pay a flat rate or one that changes by time of day. Some utilities discount certain hours, and others add demand charges or other conditions. Look up the tariff that actually applies to your household.
Public stations may price by kWh, by time connected, by session, or a mix, where permitted. A fast charger is handy on a road trip but can cost more than charging at home. Read the network's posted terms before you plug in.
| Factor | Home charging | Public charging |
|---|---|---|
| Price source | Household utility tariff | Charging-network tariff |
| Fees to include | Electricity plus possible equipment costs | Energy or time fees, possible session/parking fees |
| Main advantage | Convenience when available | Access away from home |
| Main limitation | Parking and installation availability | Variable pricing, availability, and charging speed |
How to calculate electric-car cost per mile
EV efficiency is often given in kWh per 100 miles. In this hypothetical example, the car uses 30 wall kWh per 100 miles, charging losses already included, and electricity costs $0.18 per kWh:
Energy cost per mile = (30 ÷ 100) × $0.18 = $0.054, or approximately 5.4 cents per mile.
If the consumption figure measures battery energy instead, divide it by charging efficiency once before applying the wall-energy price. Do not add another loss factor to wall-energy or EPA consumption figures that already include charging losses. You can then compare the result with a gasoline car's cost per mile, based on its miles per gallon and the price of fuel.
Energy is only part of what a car costs. Insurance, tires, depreciation, financing, and maintenance can change the overall comparison.
What affects the accuracy of the estimate?
- The difference between usable and gross battery capacity.
- Temperature, battery conditioning, and charging equipment losses.
- The charge level you start from and the level you want to reach.
- Differences between home and public electricity rates.
- Per-minute, parking, idle, and session fees.
- Vehicle efficiency, traffic, speed, and driving conditions.
Frequently asked questions
Is charging from 20% to 80% cheaper than a full charge?
Usually, yes, because it adds less energy and you pay for fewer kWh at the same price. Losses and extra fees affect the exact cost.
How much does it cost to charge an EV for 100 miles?
Multiply the car's kWh per 100 miles by the price per kWh, then adjust for charging losses and fees.
Is home charging always cheaper?
Not always, though it often is. It depends on local tariffs, network prices, when you charge, and equipment costs.
Can I calculate a full charge using battery size alone?
No. You also need the starting charge level, the energy price, and an allowance for losses, plus any extra charging fees.
Next step
Compare home and public charging in the EV Charging Cost Calculator, using your real utility price and the rate the charging network currently shows.
Note: every electricity price and charging-efficiency figure in the examples is illustrative. Replace them with current local rates before you budget.
Sources and further reading
- U.S. Department of Energy: Charging electric vehicles at home ↗
- U.S. Department of Energy: Electric vehicles for consumers ↗
- DOE/EPA: Electric vehicles and charging-efficiency boundaries ↗
Examples are hypothetical unless explicitly stated. Verify current rules and contract terms for your situation. Read the full disclaimer.
Save the guide, collect the missing evidence, and revisit your numbers before committing.
