Amps to HP Calculator
Convert full-load current (amps) to motor horsepower (HP) for single-phase and three-phase motors.
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hp
Formula: hp = (A × V × PF × η) ÷ 746
How to convert Amps to HP
The formula for a single-phase AC motor is HP = (Amps × Volts × PF × Efficiency) / 745.7.
For example, a motor drawing 21.6A at 240V with a 0.8 power factor and 90% efficiency produces exactly 5 HP. For three-phase systems, remember to multiply by the square root of 3 (1.732).
Common Amps to HP Conversions (240V, Single-Phase, 0.8 PF, 0.9 Eff)
| Current (Amps) | Voltage | Horsepower (HP) |
|---|---|---|
| 4.3 A | 240V | 1 HP |
| 8.6 A | 240V | 2 HP |
| 12.9 A | 240V | 3 HP |
| 21.6 A | 240V | 5 HP |
| 43.1 A | 240V | 10 HP |
Frequently Asked Questions
Why do I need efficiency and power factor?
Motors are not 100% efficient, and AC inductive loads have a power factor. These two values represent the real mechanical power produced vs. the total electrical power consumed.
What is a typical motor efficiency?
Standard electric motors range from 85% to 95% efficiency. We use 90% (0.9) as a standard default if the nameplate value is unknown.
What is 1 HP in watts?
One mechanical horsepower is exactly 745.7 watts.