Amps to HP Calculator

How to Convert Amps to Horsepower (HP)

In electrical engineering, you often need to convert amperes (A) to horsepower (HP) to evaluate motor performance, ensure proper circuit sizing, and select equipment. The process involves voltage, efficiency, and phase type.

Conversion Formulas

Horsepower is calculated differently depending on the type of power supply:

• Single-phase: HP = (V × I × Efficiency) ÷ 746
• Three-phase: HP = (√3 × V × I × Efficiency) ÷ 746

What You Need

• Amps (I): Electrical current flowing into the load.
• Voltage (V): Electrical potential of the system.
• Efficiency: How much power is converted to useful mechanical work. Typically 0.85–0.95.
• Phase: Whether the system is single- or three-phase.

Example Calculations

• Single-phase, 20A, 240V, 90% efficient:
  HP = (240 × 20 × 0.9) ÷ 746 ≈ 5.79 HP
• Three-phase, 25A, 480V, 92% efficient:
  HP = (√3 × 480 × 25 × 0.92) ÷ 746 ≈ 25.57 HP

Why Convert Amps to Horsepower?

This conversion helps you:

• Size motors based on available electrical current
• Select appropriate overload protection and conductors
• Estimate motor output from electrical supply
• Convert circuit capacity into mechanical performance

Motor Reference Table

Common Efficiency Ranges

• Small motors: 0.85–0.90
• Medium motors: 0.90–0.93
• Large motors: 0.93–0.96

Frequently Asked Questions