Motor Full-Load Current Calculator

How it is calculated

The tool converts the shaft (output) power into the current drawn from the supply. Three-phase: I = P ÷ (√3 × V × PF × η). Single-phase: I = P ÷ (V × PF × η). Here P is the rated output in watts (you type kilowatts and it multiplies by 1000, so horsepower must be converted first), V is the line voltage in volts, PF is the power factor as a decimal between 0 and 1, and η is efficiency typed as a percent, for example 90, not 0.9. It also reports the apparent input power in kVA, √3 × V × I ÷ 1000 (or V × I ÷ 1000 for single phase). A power factor above 1, or any zero or negative value, gives no result.

Common mistakes

• Typing efficiency as 0.9 instead of 90. The tool divides by 100, so 0.9 would be read as 0.9% and the current would come out about 100 times too high.
• Entering the power in horsepower. The field is in kW, so 10 hp must first be converted to about 7.5 kW.
• Entering the phase-to-neutral voltage (230 V) for a three-phase motor. The formula expects the line-to-line voltage, for example 400 V.
• Treating the result as a safe breaker or cable rating. It is the nominal running current, and protection and cable sizing add margins and follow local code.