Motor Current Calculator – Full Load Current (FLA/FLC)

Full Load Current (FLC), also called Full Load Amps (FLA), is the steady running current at rated output. It is the starting figure for cable, contactor and overload selection.

This tool works as a kW to amps, HP to amps and FLA calculator for 3-phase, single-phase and DC motors at any voltage up to 1000 V. For heaters and other non-motor loads, use the kW to Current Calculator.

Motor Current Formula

I = current (A) · kW = rated shaft output · V = voltage (line-to-line for 3-phase) · PF = power factor · η = efficiency as a decimal.

Motor Current Examples

Motor Current Table: kW to Amps (3-Phase)

Estimated full-load current at PF 0.85 and 90% efficiency — the calculator defaults, so you can reproduce any row. Scroll inside the table.

These are estimated running-current values based on assumed PF and efficiency. Small motors usually have lower PF and efficiency, so their real FLC is often higher than shown. Actual full-load current depends on nameplate data, design, voltage and operating conditions — use the nameplate and applicable standards for final design.

Single-Phase Motor Current Table

Small single-phase motors run at lower PF and efficiency. This table assumes PF 0.80 and 80% efficiency.

Illustrative estimates only. Capacitor-start and capacitor-run motors differ — check the nameplate.

Motor Current Examples by Region

Typical supply voltages worldwide, calculated at PF 0.85 and 90% efficiency.

FLA vs FLC vs Rated Current

Why a Formula Estimate Differs from the Nameplate FLA

The formula is exact physics, but its inputs are assumptions. Current is inversely proportional to efficiency × power factor, and both vary with rating, pole count, design and efficiency class: small and low-speed motors run at noticeably lower power factor and efficiency than large two- and four-pole machines, so a single PF 0.85 / 90% assumption underestimates small-motor current and can slightly overestimate large-motor current. For reference, the IE3 minimum efficiencies in IEC 60034-30-1 for four-pole 50 Hz motors rise from about 82.5% at 0.75 kW to about 91.4% at 11 kW and 95% at 75 kW; the calculator shows the IE3 figure for your rating when a three-phase shaft-output rating is entered, so you can see how far your efficiency assumption is from it. Power factor has no equivalent standard minimum and must come from the data sheet.

If you enter the nameplate FLA in the cross-check field, the calculator back-calculates the efficiency × power factor product the nameplate implies: η·PF = P ÷ (√3 × V × I) for three-phase. A plausible result (roughly 0.6–0.9 depending on size) confirms the reading; a result far outside that range usually means the wrong voltage column of a dual-voltage nameplate, an HP/kW mix-up, or a service-factor amps value read as FLA. Whenever the nameplate is available, it — not the formula — is the value for overload settings and equipment selection under IEC practice; under the US NEC, conductors and short-circuit protection use the code table FLC instead, as explained below.

Why FLC Drives Every Downstream Choice

Cable: needs enough ampacity for the installation method, ambient temperature, grouping and voltage drop — size it with the Cable Size Calculator, then check the run with the Voltage Drop Calculator.

Contactor: rated for the motor current under AC-3 duty.

Overload relay: set from the nameplate current, relay class and code/manufacturer rules.

Short-circuit protection: chosen per code and must ride through starting current (often 5–8× FLC for DOL).

How to Use This Calculator

1. Pick Three Phase, Single Phase or DC.
2. Enter rated power in kW or HP, and choose shaft output or electrical input.
3. Enter voltage, PF and efficiency (nameplate values if available; 0.85 PF and 88–92% are typical planning values for mid-size motors).
4. Choose a starting method to see a typical inrush range. Results update as you type.

Common Mistakes

• Forgetting efficiency. Using shaft kW as input power understates FLC by 10% or more.
• Dividing by efficiency twice. If your kW is already electrical input, don't apply η again.
• One PF for every size. Small and lightly loaded motors run at lower PF.
• Missing or wrongly adding √3. The error is a factor of about 1.73.
• Treating a fixed % as code sizing. Allowances depend on local code and starter type.

NEC FLC Table vs Actual Motor FLA

Under the US NEC, conductor and short-circuit protection sizing for most motors uses the standardised FLC tables, not the nameplate. Overload protection uses the nameplate FLA.

Table values are fixed per HP and voltage, so they differ from a formula result using a specific motor's PF and efficiency. Low-speed, high-torque and multispeed motors use nameplate values instead.

Three-phase induction motors — selected NEC Table 430.250 values (A):

Single-phase motors — selected NEC Table 430.248 values (A):

Selected values for reference; the 230 V column applies to 220–240 V systems and 460 V to 440–480 V. Confirm against the NEC edition adopted in your jurisdiction. In Canada, apply CSA C22.1 requirements for the applicable edition. Do not mix these US table values with IEC/BIS practice.

Quick NEC answers: 15 HP, 240 V 3-phase → 42 A · 10 HP, 208 V 3-phase → 30.8 A · 5 HP, 208 V single-phase → 30.8 A · 200 HP, 460 V → 240 A · 75 HP, 480 V → 96 A.

Finding the FLA of a Specific Motor Model

Catalog numbers (like those printed on NEMA-frame or DC motors) map to one manufacturer datasheet. A generic formula cannot give that exact value.

Read the nameplate or the manufacturer's datasheet at the connected voltage. Note FLA, SFA, service factor, code letter, efficiency and PF — then use this calculator only to cross-check.

MCA vs FLA

MCA (Minimum Circuit Ampacity) on HVAC and packaged equipment is a code-derived conductor figure. It typically includes 125% of the largest motor plus other loads, so it cannot be converted back to one motor's FLA. Use the FLA/RLA values on the same nameplate.

FLC is the running current. At start, an induction motor briefly draws far more — how much depends on motor design, supply strength and starting method.

DOL is simplest and cheapest but gives the highest inrush and mechanical shock — fine for small motors on a strong supply.

Star-delta, soft starters and VFDs reduce inrush, protect belts and couplings, and limit voltage dips for larger motors or weak supplies.

The calculator's starting range is a typical estimate only. For a real figure, use the locked-rotor current from the nameplate code letter or datasheet, or the Motor Starting Current Calculator.