Motor FLC Calculator
Calculate full load current (FLA) for single and three-phase AC motors. Get NEC overload relay, breaker, and wire sizing recommendations instantly.
How to Use the Motor FLC Calculator
Calculate motor full load current and NEC sizing in three steps.
Enter Motor Specs
Input HP, voltage, phase, frequency, efficiency, and power factor. Use the preset buttons for common HP values.
Click Calculate
Get full load current using I = (HP × 746) / (V × Eff × PF) for single-phase or I = (HP × 746) / (1.732 × V × Eff × PF) for three-phase.
Review NEC Sizing
Check NEC overload relay size (125% of FLC), breaker size (250%), and recommended wire gauge based on ampacity.
Common Motor FLC Reference Table
Typical full load currents for standard induction motors at 60 Hz.
| HP | Single-Phase 240V | Three-Phase 240V | Three-Phase 480V |
|---|---|---|---|
| ½ | 3.2 A | 2.0 A | 1.0 A |
| 1 | 6.4 A | 3.6 A | 1.8 A |
| 2 | 12.0 A | 6.4 A | 3.2 A |
| 3 | 17.0 A | 9.6 A | 4.8 A |
| 5 | 28.0 A | 15.2 A | 7.6 A |
| 7½ | 40.0 A | 22.0 A | 11.0 A |
| 10 | 52.0 A | 28.0 A | 14.0 A |
| 15 | — | 42.0 A | 21.0 A |
| 20 | — | 54.0 A | 27.0 A |
| 25 | — | 68.0 A | 34.0 A |
Frequently Asked Questions
Common questions about motor full load current calculations.
Single-phase: I = (HP × 746) / (V × Eff × PF). Three-phase: I = (HP × 746) / (1.732 × V × Eff × PF). Where HP is horsepower, V is voltage, Eff is efficiency as decimal, PF is power factor as decimal.
Per NEC 430.32, overloads should be sized at 125% of motor FLC for motors with service factor ≥ 1.15. For other motors, use 115%. This calculator uses 125% as the default safety factor.
Per NEC 430.52, branch circuit breakers should be sized at 250% of motor FLC for inverse time breakers. This accounts for the high inrush current (typically 600-800% of FLC) during motor startup.
FLC (Full Load Current) and FLA (Full Load Amperage) are often used interchangeably. Both refer to the current drawn by a motor when operating at its rated horsepower and voltage under full load conditions.
Induction motors draw 6-8 times their full load current during startup (locked rotor current / LRA). This is why breakers and fuses must be sized at 250% of FLC to prevent nuisance tripping during motor starting.