5 HP to Amps
Enter motor horsepower, voltage, phase, power factor and efficiency to calculate full-load amps (FLA) instantly. Results follow the NEC motor-sizing formula.
When sizing breakers and wiring for a 5 HP motor, expect a current draw of roughly 20.32 Amps at 240V (single-phase). If you're using three-phase industrial power, the FLA is around 13.53 Amps at 208V and 5.86 Amps at 480V.
5 HP is 21.19 A at 230 V single-phase AC with a power factor of 0.85. At other common voltages — 115 V: 42.38 A. Use the calculator below for any voltage or circuit type.
These estimates are derived using the standard base formula and assume a motor efficiency of 90% and a power factor of 0.85. The three-phase math includes the standard
| Phase & Voltage | Estimated FLA (Amps) |
|---|---|
| Single-phase 120V | 40.63 A |
| Single-phase 240V | 20.32 A |
| Three-phase 208V | 13.53 A |
| Three-phase 480V | 5.86 A |
How do you convert HP to amps for a motor?
Multiply horsepower by 746 (watts per HP), then divide by the product of voltage, power factor and efficiency. For a 5 HP single-phase motor at 230 V, PF 0.85, η 0.90: A = (5 × 746) ÷ (230 × 0.85 × 0.90) = 3730 ÷ 175.95 = 21.2 A.
This formula is consistent with NEC Article 430. NEC Tables 430.248 and 430.250 provide standardised full-load amps for common voltage/HP ratings and are the values legally required for conductor and breaker sizing; use this calculator for quick estimates and always cross-check with the applicable NEC table and motor nameplate.
HP to Amps Reference Table (Typical Motor FLA)
| Motor HP | Single-phase 120 V | Single-phase 230 V | Three-phase 230 V | Three-phase 460 V |
|---|---|---|---|---|
| 1 HP | 9.8 A | 5.1 A | 3.4 A | 1.7 A |
| 2 HP | 19.5 A | 10.2 A | 6.8 A | 3.4 A |
| 5 HP | — | 25.4 A | 16.9 A | 8.5 A |
| 10 HP | — | 50.9 A | 33.9 A | 17.0 A |
| 25 HP | — | — | 84.7 A | 42.4 A |
| 50 HP | — | — | 169.5 A | 84.7 A |
Calculated at PF 0.85, efficiency 0.90. Always verify against the motor nameplate and NEC Tables 430.248/430.250.
Formula
Three-phase: A = (HP × 746) ÷ (√3 × V × PF × η)
DC: A = (HP × 746) ÷ (V × η)
Where: HP = rated horsepower, V = supply voltage in volts, PF = power factor (0–1), η (eta) = motor efficiency (0–1), √3 ≈ 1.7321 for three-phase systems.
In practice: a 5 HP compressor or lathe
A 5 HP single-phase motor is listed at 56 A on 115 V and 28 A on 230 V. The 115 V figure is effectively theoretical, since nothing this size ships wired for it. On 230 V the 28 A running current calls for 10 AWG conductors, with overload protection set from the nameplate current and short-circuit protection sized from the table value — Article 430 treats those two as deliberately different.
Frequently Asked Questions
Use the formula A = (HP × 746) ÷ (V × PF × η). For example, a 5 HP motor at 230 V, PF 0.85, efficiency 90 % draws approximately 21.2 A.
For three-phase AC use: A = (HP × 746) ÷ (√3 × V × PF × η). The √3 ≈ 1.7321 factor accounts for the three-phase supply. A 10 HP motor at 460 V, PF 0.85, efficiency 90 % draws about 12.2 A.
NEC Tables 430.248 and 430.250 give standardised FLA values for conductor and breaker sizing per NFPA 70. They may differ from the formula because they represent typical motor characteristics rather than specific nameplate values.
Standard induction motors typically have PF 0.80–0.90 and efficiency 85–95 % at rated load. If the nameplate is unavailable, PF 0.85 and efficiency 90 % are conservative defaults commonly used in load-estimating.
A 1 HP single-phase 230 V motor at PF 0.85, efficiency 85 % draws about 4.5 A. At 120 V the same motor draws roughly 8.6 A. Always check the motor nameplate for the actual full-load current rating.