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EV Charging Cost Calculator
Use this free EV charging cost calculator to find out exactly what a charge will cost and how long it will take. Enter your battery size, the charge range you want, your electricity rate and your charger power, and it works out the energy needed, the cost in dollars, and the charging time. It covers home wall chargers, public chargers and fast chargers, with presets for typical rates and charger powers.
Home AC charging is usually 85–90% efficient.
How the EV charging cost calculator works
The maths has three steps. First, the energy your battery needs to store: stored energy = battery size × (target % − current %) ÷ 100. A 75 kWh battery charged from 20% to 80% stores 75 × 0.60 = 45 kWh. Second, the energy you actually pay for, because charging is never perfectly efficient: energy from the wall = stored energy ÷ efficiency. At 90% efficiency, 45 ÷ 0.90 = 50 kWh comes out of your wall socket, and the other 5 kWh is lost as heat. Third, the cost: cost = energy from the wall × electricity rate. At $0.17 per kWh, 50 × 0.17 = $8.50.
Charging time uses the same wall energy: time = energy from the wall ÷ charger power. On a 7 kW home charger, 50 ÷ 7 = 7.1 hours — an overnight charge. On a 150 kW fast charger the same energy would take 50 ÷ 150 = 20 minutes in theory, but in practice fast charging slows down sharply above 80% to protect the battery, so a real fast-charge session from 20% to 80% takes closer to 25–30 minutes. This calculator gives the steady-power figure, which is accurate for home and workplace AC charging and a useful lower bound for fast charging.
The cost per mile line uses a typical efficiency of 3.8 miles per kWh, so 45 kWh of stored energy gives about 171–190 miles of range depending on the car and the weather. Your own car's efficiency is shown on its dashboard — a small efficient EV may do 4.5 miles per kWh, while a large electric SUV may do 3.0 — so treat the per-mile figure as a guide, not a promise.
Charging levels compared
There are three levels of charging, and the difference is mostly about power. Level 1 is a standard household outlet at about 1.4 kW, adding roughly 4–5 miles of range per hour — fine as a backup, but a full charge takes more than a day. Level 2 is a dedicated home or workplace charger at 7–22 kW, adding 25–75 miles per hour; a 7 kW home charger fills a typical battery overnight, which is why most EV owners charge this way. DC fast charging at 50–250 kW adds 100–200 miles in 20–30 minutes and is meant for road trips, not daily use.
Rates differ just as much. Home electricity commonly costs $0.12–$0.20 per kWh, and off-peak overnight rates can be under $0.10. Public AC chargers usually charge $0.25–$0.35, and DC fast chargers $0.40–$0.50 or more. That is why the same 50 kWh charge costs $8.50 at home but $22.50 at a fast charger — and why the calculator's rate presets matter. If your electricity plan has off-peak hours, scheduling the charge overnight is the single easiest way to cut your EV running costs.
Worked example
Charge a 75 kWh battery from 20% to 80% at home, at $0.17 per kWh, 90% efficiency, on a 7 kW wall charger.
Step 1: Stored energy — 75 × (80 − 20) ÷ 100 = 75 × 0.60 = 45.0 kWh.
Step 2: Energy from the wall — 45.0 ÷ 0.90 = 50.0 kWh (5 kWh lost as heat).
Step 3: Cost — 50.0 × $0.17 = $8.50.
Step 4: Charging time — 50.0 ÷ 7 = 7.1 hours, so plug in at 10 pm and it is ready by 5 am.
Step 5: Range — 45 kWh × 3.8 miles per kWh ≈ 171 miles of driving, at about $8.50 ÷ 171 = $0.05 per mile.
Compare that with the same charge at a fast charger at $0.45 per kWh: the energy is the same 50 kWh, but the cost is 50 × 0.45 = $22.50, while the time drops to about 20–30 minutes. Home charging saves $14.00 on this one session — over a year of weekly charging, that is more than $700.
FAQ
How much does it cost to charge an electric car at home?
Multiply the energy you need by your electricity rate. A 75 kWh battery charged from 20% to 80% needs 45 kWh of stored energy, and at 90% charging efficiency that is 50 kWh from the wall. At a home rate of $0.17 per kWh that costs $8.50. The same charge at a public fast charger at $0.45 per kWh costs about $22.50, so home charging is usually two to three times cheaper.
How long does it take to charge an EV?
Divide the energy needed by the charger power. A 50 kWh charge on a 7 kW home charger takes 50 ÷ 7 = about 7.1 hours, while the same 50 kWh on a 150 kW fast charger takes about 20 minutes in theory — in practice longer, because charging slows down above 80%. A standard wall outlet at 1.4 kW would take over 35 hours for the same charge.
What is charging efficiency, and why does it matter?
Charging efficiency is the share of the electricity from the wall that actually ends up stored in the battery. The rest is lost as heat in the charger, the cables and the battery itself. Home AC charging is typically 85 to 90% efficient, so a battery that needs 45 kWh of stored energy draws about 50 kWh from the wall. You pay for the wall energy, not the stored energy, which is why this calculator includes the efficiency setting.
Why do most people charge from 20% to 80%?
Two reasons. First, charging is fastest in the middle of the range: a battery accepts full power up to about 80%, then slows sharply to protect the cells, so the last 20% can take as long as the first 60%. Second, keeping the battery between 20% and 80% most of the time reduces wear and extends its life. Charging to 100% is fine before a long trip — just do it shortly before you leave.
Is charging an EV cheaper than petrol?
Usually, yes — especially at home. A 50 kWh home charge costing $8.50 gives roughly 170 miles of range, or about 5 cents per mile. A petrol car doing 30 miles per gallon at $3.50 a gallon costs about 12 cents per mile, so the EV costs roughly a third as much per mile. Public fast charging narrows the gap but is still usually cheaper than petrol.