Work out what an EV charge really costs from battery size, charge window and your electricity rate, with charge times by charger power from 7 to 150 kW. Runs entirely in your browser — your numbers never leave this device.
| Charger power | Time (minutes) | Time |
|---|---|---|
| 7 kW | 308.57 | 5 h 09 min |
| 11 kW | 196.36 | 3 h 16 min |
| 22 kW | 98.18 | 1 h 38 min |
| 50 kW | 43.2 | 43.2 min |
| 150 kW | 14.4 | 14.4 min |
Times assume the charger holds its full rated power for the whole session. Real charging tapers as the battery fills — especially past about 80% — so treat the table as a best case. The rate is the one you type in; no tariff data is stored or fetched.
| Charger power | Minutes | Hours |
|---|---|---|
| 7 kW | 308.6 | 5.14 |
| 11 kW | 196.4 | 3.27 |
| 22 kW | 98.2 | 1.64 |
| 50 kW | 43.2 | 0.72 |
| 150 kW | 14.4 | 0.24 |
An EV charge is priced on energy, and the energy in a partial charge is a simple proportion of the battery: a 60 kWh pack charged from 20% to 80% takes 60% of its capacity, which is 36 kWh, and at a rate of 0.30 per kWh that session costs 10.80. The same arithmetic prices any window on any pack — from 10% to 90% of a 75 kWh battery is 60 kWh — which is why the useful habit is to think in kWh added rather than percentages: the percentage is only meaningful once the capacity turns it into energy.
Charge time is the same energy divided by charger power, and here the page is deliberately labelled idealised. The table assumes the charger delivers its full rated power from the first minute to the last, so 36 kWh at 7 kW takes 308.6 minutes and at 150 kW takes 14.4 minutes. Real charging does not hold peak power: the car tapers the rate as the battery fills, sharply so past about 80%, the charger and the car's onboard limit may both sit below the headline figure, and cold batteries charge slower. Treat the table as the floor under the real time — the fastest the session could possibly go — and expect a real 20–80% session to land above it.
The rate is always the one you type in. Home tariffs, time-of-use windows and public rapid-charging prices differ severalfold from each other and change without notice, so no tariff is stored or fetched; enter the rate on your bill or the charger's price screen and the cost comes back in that currency. Note also that the calculation prices the energy that reaches the battery — charging losses in the cable and converter mean the meter supplies somewhat more than the battery stores, so a bill-based cost per charge runs slightly above the figure here.
Two practical reasons meet in that window: charging speed tapers hard at high states of charge, so the last fifth takes a disproportionate share of the session, and holding a battery at full charge is harder on its long-term health than mid-range cycling. The arithmetic here works for any window — 10% to 90% of a 75 kWh pack is 60 kWh — but 20–80% is the window most drivers actually buy.
The table is idealised: it holds the charger's rated power constant, and real charging tapers as the battery fills, especially past about 80%. The car's own maximum charge rate may also be below the charger's, and a cold battery accepts less. Read the table as a best case — 36 kWh cannot arrive faster than 14.4 minutes even at 150 kW.
Usable, if the maker publishes it, because the percentage gauge tracks the usable portion — the energy this formula multiplies. Using a larger gross figure overstates every window by the same proportion. If only one capacity is published, use it consistently and compare like with like.
Entirely through the rate you enter: the energy is identical, so cost scales with price per kWh. The 36 kWh session in the examples costs 10.80 at 0.30 per kWh and would cost 27.00 at 0.75 — the calculator's job is to make that multiplication exact for your tariff, not to guess which tariff you are on.
No — it prices the energy stored in the battery. The meter supplies more than that, because the charger, cable and the car's converter each lose a share as heat. For a bill-accurate figure, note your meter's kWh for a session and price that quantity at your rate instead.
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