Horsepower to Amps Calculator
Enter horsepower, volts, and motor efficiency below to convert to amps.
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How to Convert Horsepower to Amps
Horsepower (HP) is a measure of electric power equal to 746 watts (W). Converting horsepower to amps can be done in a few simple steps, or using this simple formula.
Amps = (Horsepower × 746) ÷ Efficiency ÷ Volts
Continue reading to see how this formula was derived.
Convert Horsepower to Watts
The first step to convert HP to amps is convert HP to watts. Since 1 HP is equal to 746 W simply multiply the horsepower by 746 for this conversion.
Watts = Horsepower × 746
Account for Efficiency
Since motors are not 100% efficient, the number of amps needed to achieve the power output is actually higher depending on the efficiency. To find this, divide the horsepower by the efficiency η in decimal form.
Watts = Watts / η
Convert to Amps
After the power has been converted to watts, use the Watt’s Law formula to find current in amps.
Amps = Watts ÷ Volts
After the steps above the final formula for converting horsepower to amps is:
Amps = HP × 746 / V × η × PF
Thus, the current in amps is equal to horsepower times 746 divided by the voltage times the efficiency η times the power factor.
For example, let’s find the current draw in amps of a 1 horsepower motor that runs at 120 volts with a 90% efficiency.
Amps = 1 HP × 746 W / 120 V × .9
Amps = 746 / 120 V × .9
Amps = 746 / 108
Amps = 6.9 A
Common Horsepower to Amps Conversions
|.25 HP||1.73 A||120 V||90%|
|.5 HP||3.45 A||120 V||90%|
|.75 HP||5.18 A||120 V||90%|
|1 HP||6.91 A||120 V||90%|
|1.25 HP||8.63 A||120 V||90%|
|1.5 HP||10.4 A||120 V||90%|
|1.75 HP||12.1 A||120 V||90%|
|2 HP||13.8 A||120 V||90%|
|2.5 HP||17.3 A||120 V||90%|
|3 HP||20.7 A||120 V||90%|
|3.5 HP||24.2 A||120 V||90%|
|4 HP||27.6 A||120 V||90%|
|4.5 HP||31.1 A||120 V||90%|
|5 HP||34.5 A||120 V||90%|
|10 HP||69.1 A||120 V||90%|
Also be sure to check out our amps to horsepower calculator.