Motor formula tool
Horsepower and Amps Calculator
Enter HP, voltage, phase, efficiency, and PF to estimate motor formula current before NEC FLC or nameplate FLA review.
Convert Horsepower and Amps
Enter HP, voltage, phase, efficiency, and power factor to estimate formula current. Compare NEC FLC and nameplate FLA before motor sizing.
Result
Amps
11.73 A
Result notes. Keep inputs, assumptions, and result together before using this value in project records.
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Motor Current Calculator
Estimate formula running current from HP or kW, voltage, efficiency, and power factor, then compare against NEC table FLC when needed.
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Open the motor power calculator to continue the workflow review.
Full Load Current Calculator
Owns NEC Table 430.248/430.250 FLC lookup by HP, voltage, and phase, including 10 HP and 200 HP at 460V field checks.
Three Phase Motor Calculator
Balanced three-phase operating-point screen for line current, input kW, kVA, kVAR, and estimated shaft output.
Related charts
HP to Amps Chart
Use this HP to amps chart: 1 HP at 240V 1-phase = 4.3A, 10 HP at 480V 3-phase = 11.2A, with 90% efficiency and 0.80 PF.
Motor Full Load Amps Chart
Plan motor full-load amp work by separating table FLC, nameplate FLA, formula estimates, starting current, overloads, and branch-circuit protection.
Motor Power HP kW Chart
Use a motor power HP kW chart to document horsepower, mechanical output, electrical input, kVA, kVAR, power factor, efficiency, and current context after the calculator result.
Related guides
Motor Power Formulas Guide | HP, kW, Torque and Current
Use this motor power formulas guide to choose HP, kW, torque, speed, efficiency, power factor, voltage, and calculator inputs.
Motor Starting Methods Guide | DOL, Soft Starter, VFD
Use this motor starting methods guide to choose DOL, star-delta, autotransformer, soft starter, VFD, voltage-drop, and torque checks.
Related tools
Formula and field context
Enter HP, voltage, phase, efficiency, and PF to estimate motor formula current before NEC FLC or nameplate FLA review.
Formula context
HP to Amps Chart
Quick answer: with 90% efficiency and 0.80 PF, 1 HP is about 4.3 A at 240 V single-phase, 5 HP is about 5.6 A at 480 V three-phase, and 10 HP is about 11.2 A at 480 V three-phase. Use the calculator when nameplate FLA, NEC FLC, or starting duty matters.
Formula
Single phase estimate: A = HP x 746 / (V x efficiency x PF). Three phase estimate: A = HP x 746 / (1.732 x VLL x efficiency x PF).Variables to keep with the result
- HP is mechanical horsepower.
- Efficiency is motor efficiency entered as a decimal.
- PF is motor power factor entered as a decimal.
- V or VLL is the voltage used by the motor connection.
Formula and assumptions
Electrical input current can be estimated from horsepower by converting HP to watts, then dividing by voltage, phase factor, power factor, and motor efficiency. The formula is useful for planning, but it is not the same as NEC table full-load current or actual nameplate FLA.
U.S. motor context
Electricians often need a reasonableness check when a motor nameplate, equipment schedule, or control panel note lists HP but not current. Enter the motor voltage, phase, efficiency, and PF in the calculator, then treat the result as a formula estimate rather than a final branch-circuit current.
When to use the full calculator
Move to the motor-current and full-load-current calculators when conductor sizing, overloads, breaker settings, starter sizing, or NEC motor rules matter. This worksheet stays limited to the HP and amp relationship.