Motor Full-Load Amps Calculator

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Three-phase uses sqrt(3) x line-to-line voltage. Single-phase uses voltage x current. DC ignores power factor.
Mechanical motor output rating. In Imperial units this displays as horsepower; in SI it displays as kW.
hp
Line-to-line voltage for three-phase motors, line voltage for single-phase motors, or DC terminal voltage.
V
Output mechanical power divided by real electrical input power, as a percent.
%
AC real-power factor. DC mode ignores this field.
Multiplier used to show approximate service-factor current, not a protection rule.
Applied to the formula FLA before comparing with the entered circuit or ampacity limit.
%
Entered reference current for utilization and margin. This can be a planned circuit rating, conductor ampacity or equipment limit.
A

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Formula full-load amps(I_fla)
11.72A
Pass

Three-phase current = Pout / (efficiency x sqrt(3) x voltage x power factor).

Also computed

Design current(I_design)Pass14.66A

Formula FLA multiplied by the entered design-current multiplier.

Service-factor current(I_sf)13.48A

Formula FLA multiplied by the entered service factor.

Real input power(P_in)11.11hp

Mechanical output power divided by motor efficiency.

Apparent power(S)9.748kVA

AC apparent power = real input kW / power factor.

Selected-current utilization(U)Pass73.28%

Design current divided by the entered selected current.

Current margin(I_sel - I_design)Pass5.344A

Positive margin against the entered selected current.

Motor current preview M RUNNING DESIGN SERVICE FACTOR 11.7 A running 14.7 A design load
Method notes 3 notes
  • Three-phase current = Pout / (efficiency x sqrt(3) x voltage x power factor).
  • This is a formula current estimate from entered motor data. It is not an NEC motor full-load-current table, branch-circuit protection selector, overload setting or nameplate replacement.
  • Final motor circuits still need nameplate FLA, duty cycle, starting/inrush, VFD behavior, conductor ampacity, voltage drop, overload protection, short-circuit protection, grounding and local code review.

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