HP to Amps Chart

Convert horsepower to estimated motor running current at common U.S. voltages, then move to the motor calculator when voltage, efficiency, PF, NEC table FLC, nameplate FLA, or starting duty matters.

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Quick reference table

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-based motor running-current screen

Formula-based motor running-current screen
Motor size	240 V 1-phase	208 V 3-phase	480 V 3-phase	Assumption
1 HP	4.3 A	3.0 A	1.3 A	90% eff, 0.80 PF
3 HP	13.0 A	9.0 A	3.9 A	90% eff, 0.80 PF
5 HP	21.6 A	15.0 A	5.6 A	90% eff, 0.80 PF
10 HP	43.2 A	29.9 A	11.2 A	90% eff, 0.80 PF
25 HP	107.9 A	74.8 A	28.1 A	90% eff, 0.80 PF

HP-to-amps chart to motor calculator handoff

HP-to-amps chart to motor calculator handoff
Search or worksheet need	Use this chart for	Open the motor calculator when
HP to amps chart	Screening a motor schedule before full nameplate data is available	Voltage, efficiency, PF, NEC FLC, or nameplate FLA must stay with the result
Three-phase HP to amps	Comparing line-voltage rows for an early running-current estimate	Conductor, overload, breaker, starter, or generator review is next
Motor FLA or FLC comparison	Seeing why formula current, nameplate FLA, and NEC table FLC are separate	The task requires an installed-equipment or code-sensitive current basis

Which motor current value belongs in which decision

Which motor current value belongs in which decision
Decision	Current basis to verify	Why the chart is not enough
Load estimate	Formula current or nameplate input current	Good for early panel or generator screening
Conductor and branch circuit	Adopted motor sizing path and table/nameplate basis	Motor rules can differ from formula current
Overload protection	Motor nameplate current and overload instructions	Nameplate FLA is usually central
Starting review	Locked-rotor, inrush, or starter method	Running current does not show voltage dip

Formula basis

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).

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.

Worked examples

Screening a fan motor scheduleA 10 HP motor is about 11.2 A at 480 V three-phase with 90% efficiency and 0.80 PF before nameplate and NEC checks.

Checking a single-phase shop motorA 1 HP motor is about 4.3 A at 240 V single-phase with the chart assumptions; use the calculator when installed motor data changes the current basis.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

The table is formula-based and does not reproduce NEC motor full-load current tables.
Nameplate current, service factor, duty, design letter, starting method, and manufacturer instructions can change the motor workflow.
The table assumes running current, not locked-rotor or starting current.

Code and standard notes. Planning limits that should be checked before final equipment selection.

For motor conductors, overloads, short-circuit and ground-fault protection, controller selection, and disconnecting means, verify the adopted NEC edition, equipment nameplate, manufacturer instructions, and AHJ requirements.

How to use this chart

1Use it before the nameplate is completeUse the chart for early pump, fan, compressor, conveyor, or shop-equipment screening when horsepower is known but full motor data is not ready.

2Record motor phase and voltageWrite the actual motor connection voltage and whether the motor is single-phase or three-phase before comparing rows.

3Separate running and starting currentUse this page for running-current estimates only, then use the starting-current workflow for inrush, voltage dip, or generator sizing concerns.

4Move code work to the motor calculatorBefore conductors or protection are selected, use the motor calculator and verify nameplate, adopted NEC, manufacturer, and AHJ requirements.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Record horsepower sourceIdentify whether HP came from a motor nameplate, equipment submittal, pump schedule, preliminary design, or replacement request.
Attach efficiency and PF basisUse measured, nameplate, manufacturer, or conservative assumed values for efficiency and PF, and label the assumption clearly.
Document motor decision pathMark whether the current is for load estimating, conductor review, overload setup, starter selection, generator sizing, or troubleshooting.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Using the formula estimate as if it were the required NEC motor full-load current for every downstream sizing decision.
Ignoring efficiency and power factor, which can make estimated current look lower than real motor current.
Using running current for starting-current or voltage-dip questions where locked-rotor behavior matters.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Why does my motor nameplate show different amps?

The chart uses generic efficiency and PF assumptions, such as 10 HP at 480 V three-phase = 11.2 A. The nameplate reflects the actual motor design and is often the better source for installed equipment work.

Is HP-to-amps the same as NEC FLC?

No. This page is a formula screen. NEC motor workflows may require table values, nameplate current, overload rules, and branch-circuit protection checks.

Can I use this chart for motor starting current?

No. Starting current depends on locked-rotor characteristics, starting method, voltage, and source stiffness. Use the motor starting calculator for that review.