Amps to kW Calculator

Turn the per-phase current a PDU or panel shows into the kilowatts a rack or room is actually using.

Inputs

Result

Enter the current in amps to see the power in kW.

Related tools

How the calculation works

Real power in kilowatts comes from the current, the voltage, the circuit type and the power factor (PF):

Single-phase: kW = volts × amps × PF ÷ 1,000
Three-phase: kW = √3 × volts × amps per phase × PF ÷ 1,000, with the line-to-line voltage and √3 ≈ 1.732

The formula assumes the three phases carry roughly the same current, which is the goal when loads are spread across a three-phase PDU. If the readings differ, enter their average for an estimate.

The default is 208 V three-phase at a power factor of 1.0. A PF of 1.0 gives the highest kW for a given current, so if you know the real PF (many PDUs report it), enter it. The calculator also shows the apparent power in kVA (√3 × volts × amps ÷ 1,000 on three-phase), which does not depend on the power factor.

Reading a 415 V PDU. A three-phase PDU on a 415Y/240 V feed, used in some datacenters to run IT equipment at 240 V, typically shows a current for each of its three input lines (L1, L2, L3). Between two lines the voltage is 415 V; between one line and neutral it is 240 V (415 ÷ √3), and the outlets on a phase-to-neutral PDU run at 240 V. Enter 415 V with three-phase selected. On a 400Y/230 V feed, enter 400 V; the line-to-neutral voltage is 230 V.

Worked example

A three-phase PDU on a 415 V feed shows about 24 A on each line. The PDU reports a power factor of 0.95:

kW = 1.732 × 415 × 24 × 0.95 ÷ 1,000 = 16.39 kW
apparent power = 1.732 × 415 × 24 ÷ 1,000 = 17.25 kVA

The same 24 A per phase on a 208 V three-phase PDU is a much smaller load:

kW = 1.732 × 208 × 24 × 0.95 ÷ 1,000 = 8.21 kW
apparent power = 8.65 kVA

That difference is why a per-phase amps figure needs its voltage before you can compare it with a rack’s power budget.

Frequently Asked Questions

How many kW is 32 A three-phase at 415 V?

At a power factor of 1.0, 1.732 × 415 × 32 ÷ 1,000 = 23 kW. At a power factor of 0.95 it is 21.85 kW. That is the power at the full 32 A; a circuit planned for continuous load is usually kept well below its rating.

Do I add the three phase readings together?

Not with this formula. Enter one phase's current with three-phase selected; the √3 already accounts for all three phases. If the three readings differ, enter their average. Adding the three currents and multiplying by the line-to-neutral voltage gives the same answer as the formula; adding them and multiplying by the line-to-line voltage overstates the power by about 73%.

Why compare racks in kW rather than amps?

Amps only mean something together with a voltage and phase: 24 A per phase is 8.21 kW at 208 V three-phase but 16.39 kW at 415 V three-phase (power factor 0.95). Kilowatts compare directly across circuits, sites and countries.

Is the kW figure what I am billed for?

It depends on the contract. Some colocation agreements charge per circuit by its breaker rating, whatever you draw; others meter energy in kWh or charge for a committed kW. This calculator gives the power at one moment; energy is kW × hours.