Motor FLA & VFD Sizing Calculator
Calculate motor full-load current from HP or kW, voltage, phase, power factor, and efficiency — and get a VFD output-current sizing hint. Single-phase, three-phase, and DC. Free.
HP, kW, and full-load current
One mechanical horsepower is 745.7 W of shaft output. Full-load current is what the motor draws at rated load — higher than the shaft power implies, because you also pay for the motor's efficiency and (on AC) its power factor. This tool estimates it from those inputs; the motor nameplate is always the final word.
| HP | kW | ~FLA @ 230V 3φ | ~FLA @ 460V 3φ |
|---|---|---|---|
| 1 | 0.75 | 3.6 | 1.8 |
| 3 | 2.24 | 9.6 | 4.8 |
| 5 | 3.73 | 15.2 | 7.6 |
| 10 | 7.46 | 28 | 14 |
| 25 | 18.6 | 68 | 34 |
| 50 | 37.3 | 130 | 65 |
| 100 | 74.6 | 248 | 124 |
FLA figures above are approximate NEC 430.250 table values for conductor and protection sizing — they run higher than a pure power calculation on purpose. Use nameplate and NEC values for anything that gets inspected.
Sizing a VFD
Size a variable frequency drive by the motor's rated current, not its horsepower — a drive's HP rating assumes a "standard" motor, and yours may draw more. Match or exceed the nameplate FLA, then add margin for high-inertia loads (fans, centrifuges) or constant-torque loads (conveyors, positive-displacement pumps). New to drives? See VFD basics: how they work and common faults.