Calculate 3 phase motor horsepower from line voltage, current and power factor, or solve for voltage, current or power factor, with kW and kVA shown.

Electrical input horsepower. Add motor efficiency under Optional to also see shaft output.

0.85 is typical for an induction motor near full load; use the nameplate value if you have it. Not the same as efficiency.

Optional settings
Blank omits shaft horsepower. Use the efficiency at this load.

3 Phase Horsepower Formula

The following equation is used to calculate the horsepower in a three-phase system.

HP = (√(3) × V × I × PF) / 746
  • Where HP is electrical input power expressed in horsepower (hp), using 746 W/hp
  • V is the line-to-line voltage (V)
  • I is the line current (A)
  • PF is the power factor

Choose the unknown under Solve for and enter the three known values. The calculation assumes balanced three-phase RMS measurements.

What is a 3 Phase Horsepower Calculator?

Definition:

A 3 Phase Horsepower Calculator is a tool used to determine the missing electrical parameter in a three-phase system by leveraging the relationship between voltage, current, power factor, and horsepower.

How to Calculate 3 Phase Horsepower?

Example Problem:

The following example outlines the steps and information needed to calculate the missing parameter in a three-phase system.

First, determine the provided values. In this example, the voltage is 400 V, the current is 15 A, and the power factor is 0.85.

Next, apply these values to the formula above:

HP = (√3 × 400 × 15 × 0.85) / 746

HP = (1.732 × 400 × 15 × 0.85) / 746

HP ≈ 11.84

Thus, the electrical input is equivalent to approximately 11.84 hp. Shaft output is lower and equals this value multiplied by motor efficiency; at 90% efficiency it is approximately 10.66 hp.

FAQ

What factors can affect the horsepower calculation accuracy?

The calculation accuracy can be influenced by variations in voltage, current, and power factor due to measurement errors or load fluctuations, which can result in differences in the computed horsepower.

How do I choose the value to calculate?

Select the desired result under Solve for. Its input is hidden; enter the remaining three values and select Calculate.

Can this calculator be used for both motors and generators?

The balanced three-phase formula describes real electrical power for motors or generators. It does not directly give mechanical shaft power. The optional efficiency input estimates motor shaft output from electrical input; it is not a generator mechanical-input calculation.