Amps to Horsepower Calculator

Enter amps, volts, and motor efficiency to calculate the horsepower.

amps
volts
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Results:

  Horsepower


How to Convert Amps to Horsepower

The conversion from amps, a measure of electric current, to horsepower, a measure of power output by a motor, can be done using a fairly simple formula.

Horsepower = (Amps × Volts × Efficiency) ÷ 746

How did we get that? Since horsepower is a measure of electric power, Watt’s Law can be used to convert. Watt’s Law gives us the formula to solve power given voltage and current using this formula.

Watts = Amps × Volts

After converting amps and volts to watts, the next step is to convert watts to horsepower.

Conversion of watts to horsepower
Horsepower Watts
1 Electric HP 746 watts
1 Mechanical HP 745.7 watts

Because 1 horsepower is equal to 746 watts, the formula above will include a division by 746 to complete the conversion.

One additional consideration that should be made when doing the conversion is the efficiency of the motor being used. Motors are often only 80% to 90% efficient, which means that they can only produce 80% to 90% of energy output for the amount of power in.

When converting to horsepower the efficiency can be accounted for by multiplying the result by the efficiency in decimal form.

For example, let’s find the horsepower of a motor drawing 8 amps at 120 volts that is 90% efficient.

HP = (Amps × Volts × Efficiency) ÷ 746
HP = (8 A × 120 V × .9) ÷ 746 W
HP = 864 ÷ 746
HP = 1.158 HP

Commons Amps to Horsepower Conversions

Power measurements in horsepower for common amperage values at 120 volts for a motor with 90% efficiency.
Amps Horsepower Voltage Efficiency
1 A .14 HP 120 V 90%
2 A .29 HP 120 V 90%
3 A .43 HP 120 V 90%
4 A .58 HP 120 V 90%
5 A .72 HP 120 V 90%
6 A .87 HP 120 V 90%
7 A 1.01 HP 120 V 90%
8 A 1.16 HP 120 V 90%
9 A 1.3 HP 120 V 90%
10 A 1.45 HP 120 V 90%
15 A 2.17 HP 120 V 90%
20 A 2.9 HP 120 V 90%
25 A 3.62 HP 120 V 90%
30 A 4.34 HP 120 V 90%

We also have a horsepower to amps calculator that you may find useful.