Three-Phase EV Charging Calculator

The Three-Phase EV Charging Calculator estimates how fast a single-phase or three-phase AC supply charges your electric car once its onboard charger sets the limit.

How Many Wires Are Carrying Current

Every AC charging speed starts from one question that has nothing to do with the car: how many live wires is the supply pushing current through. A single-phase supply uses one, and its power is simply the voltage times the current, so 230 volts at 32 amps gives 230 × 32, about 7.4 kW. A three-phase supply uses three live wires at once, and its power is the square root of three times the 400-volt line voltage times the current, equivalently three times the 230-volt phase voltage times the current.

That extra factor is why phase count matters more than amperage. At the same 16 amps per wire, a three-phase supply delivers about 11 kW where a single-phase one manages under 4 kW, and at 32 amps the gap widens to roughly 22 kW against 7.4 kW. The two common three-phase levels follow directly: 16 amps per phase is the 11 kW home standard across much of Europe, and 32 amps per phase is the 22 kW figure you see on public posts. None of this is the same as the voltage inside the battery, which some EVs raise to 800 volts for DC fast charging; that is a separate lever, and why a car's pack voltage decides its fast-charge ceiling covers it. Here the count of phases at the wall is what matters, not the pack voltage.

What Each Supply Delivers to Three Kinds of Car

The table below is the heart of the tool. It takes the four common AC supplies down the left and three onboard chargers across the top, then reports the power that actually reaches the car. Read it in two directions: down a column to see how one car responds to better supplies, and across the bottom row to see how the same 22 kW supply treats three different cars.

AC Supply	Single-phase 7.4 kW car	Three-phase 11 kW car	Three-phase 22 kW car
Single-phase 16 A (3.7 kW)	3.7 kW	3.7 kW	3.7 kW
Single-phase 32 A (7.4 kW)	7.4 kW	7.4 kW	7.4 kW
Three-phase 16 A (11 kW)	3.7 kW	11.0 kW	11.0 kW
Three-phase 32 A (22 kW)	7.4 kW	11.0 kW	22.0 kW

Two patterns carry the whole page. The single-phase car column never beats 7.4 kW, and it even falls from 7.4 kW on a single-phase 32-amp socket to 3.7 kW on a three-phase 16-amp box, because a single-phase charger can only draw from one of the three phases and that box offers just 16 amps per phase. The bottom row is the mirror image: on one 22 kW supply the single-phase car takes 7.4 kW, the 11 kW car takes 11 kW, and only the 22 kW car reaches the full 22 kW. For a 60 kWh pack from 20% to 80%, those rates work out to roughly 5 hours 26 minutes, 3 hours 38 minutes, and 1 hour 49 minutes, and you can lock in one car on one charger to see your own numbers.

Your Onboard Charger Decides Whether Three-Phase Helps

The supply describes what the wall can push; the onboard charger describes what the car will pull. Every EV carries an onboard charger that converts AC to DC, and it has two ratings that matter here: a power ceiling in kilowatts, and the number of phases it can use. The car always draws the lower of what the supply offers and what the onboard charger accepts, so the rule governing every cell in the table is the minimum of supply power and onboard capacity, with the phase count deciding how much of a three-phase supply counts as available in the first place.

This is where buyers get caught. A car with an 11 kW three-phase onboard charger gains nothing from a 22 kW supply, because its own charger caps the rate at 11 kW. A single-phase-only car, common on budget and older models, ignores two of the three phases entirely and tops out near 7.4 kW whatever the supply is rated. The number worth checking before anything else is the onboard AC rating on the spec sheet, and how an onboard-charger rating reads on a spec sheet shows where it sits among the other figures. Once you know it, you can size a home charger to your supply and daily mileage rather than paying for power the car cannot accept.

Why Three-Phase Home Charging Is an EU and Australia Question

Whether any of this applies to you depends on the supply at your house, and that splits sharply by country. Across Germany, much of continental Europe, and Scandinavia, homes receive a 230-volt and 400-volt three-phase service as standard, which is why 11 kW home wallboxes are the default and most European EVs ship with three-phase onboard chargers. Australia is mostly single-phase, with three-phase increasingly fitted in newer and larger builds, so 11 kW and 22 kW home charging is possible but not the norm.

The United States and the United Kingdom are the other case. American homes use a split-phase 240-volt service that is single-phase electrically, reaching about 7.4 kW at 32 amps and up to 11.5 kW at 48 amps on one phase, with no three-phase available without a costly utility upgrade. UK homes are almost universally single-phase at around 7 kW. For drivers there, the phase question is moot and amperage is the only lever, which is the territory the what each amp delivers on a single-phase circuit chart covers, and the running-cost picture from turn the energy added into a running cost per mile looks the same whether the kilowatts arrive on one phase or three. For the wider map of how AC sits beside DC fast charging, where AC charging sits among the three levels places it in context.

Worked Example: A Single-Phase Car on a 22 kW Supply

A driver in Germany parks beside a 22 kW three-phase wallbox in a standard Peugeot e-208, whose spec sheet lists a 7.4 kW single-phase onboard charger. A single-phase charger connects to one of the three phases, so at 32 amps on a 230-volt phase it draws 230 × 32, about 7.36 kW, just under the 7.4 kW ceiling. Delivered power is 7.4 kW and the other two phases sit unused.

After the roughly 10% conversion loss the pack sees about 6.6 kW, so 50 kWh from 20% to 80% (30.0 kWh) takes about 4 hours 32 minutes, near 28 miles of range per hour. A plain single-phase 32-amp socket would charge this car at exactly the same rate, so the three-phase wallbox buys nothing on a single-phase-only car.

Worked Example: The 11 kW Car and the 22 kW Car

Two 60 kWh cars share that same 22 kW three-phase supply, one with the mainstream 11 kW three-phase onboard charger and one with the rare 22 kW unit fitted to a Renault Zoe. A three-phase charger uses all three phases, so the supply offers 3 × 230 × 32, about 22 kW. The 22 kW car draws the full amount and moves 36.0 kWh from 20% to 80% in about 1 hour 49 minutes.

The 11 kW car is held to 11 kW by its own onboard charger, so the identical 36.0 kWh takes about 3 hours 38 minutes, exactly twice as long. The supply is the same in both cases; the onboard charger is the entire story, which is why a 22 kW supply only earns its place with a 22 kW car.

Phase

A phase is one live wire carrying alternating current from the supply. A single-phase connection has one such wire plus a neutral, while a three-phase connection has three, their currents staggered so that power flows continuously. Because three wires carry roughly three times the power of one at the same per-wire current, the phase count is the single biggest lever on AC charging speed, ahead of amperage.

Onboard Charger Phase Support

Onboard charger phase support is how many of the supply’s phases a car’s built-in AC charger can actually use. A three-phase onboard charger draws on all three and reaches 11 kW or 22 kW; a single-phase one uses only one phase and tops out near 7.4 kW no matter what the supply offers. It is set by the manufacturer, often varies between a car’s home and export markets, and is the figure that decides whether a three-phase supply does anything for a given vehicle.

Per-Phase Current

Per-phase current is the amperage flowing in each live wire, and it is what separates an 11 kW three-phase supply from a 22 kW one. Sixteen amps per phase gives about 11 kW across three phases; thirty-two amps per phase gives about 22 kW. A single-phase car only ever sees the current on the one phase it uses, which is why a 16-amp three-phase box leaves it slower than a 32-amp single-phase socket.

Three-phase charging is a simple idea with one firm catch. More phases mean more power in direct proportion, but only up to what the car’s onboard charger can pull, and only where the supply at the wall actually carries three phases. Match a three-phase car to a three-phase supply and the kilowatts climb; pair either one with a single phase and the speed falls back to what one wire can carry.