Motor Current from Horsepower

Motor input power is output horsepower divided by efficiency.

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Formula

1φ: I = hp × 746 ÷ (V × η × PF)
3φ: I = hp × 746 ÷ (1.732 × V × η × PF)

Example calculation

5 hp, 230 V three-phase, 87% eff, 0.85 PF → 14.1 A.

Practical HVAC use

Sanity-check measured motor current.

Common mistakes

Sizing conductors from this estimate instead of code tables.

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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators