Watts to HorsepowerFree online conversion calculator — instant results, no sign-up
Convert watts to mechanical horsepower and back.
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About the Watts to Horsepower
The Watts to Horsepower calculator converts a power value in watts to mechanical horsepower and shows the reverse conversion factor. With the default input of 1 watt, it reports 0.001341 horsepower. This tool uses mechanical horsepower, not metric horsepower.
- Value in watts (watts)
- The power to convert, measured in watts (W), with a default value of 1.
Formula and method
P_hp = P_W / 745.699872; conversely, P_W = P_hp × 745.699872.
- P_WPower in watts.
- P_hpPower in mechanical horsepower.
Divide the entered watt value by 745.699872 to obtain mechanical horsepower, then round the displayed result. For the default input, 1 / 745.699872 gives 0.001341 horsepower when rounded to six decimal places. To convert mechanical horsepower back to watts, multiply by 745.699872.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Value in watts1 watts
Results
- horsepower0.001341
- 1 watts =0.001341 horsepower
- 1 horsepower =745.699872 watts
How to use the Watts to Horsepower
- 1Enter the power in the Value in watts (watts) field, or leave the default value of 1.
- 2Read the horsepower result calculated by dividing the watt value by 745.699872.
- 3Check the forward-conversion row: with the default input, it displays 1 watts = = 0.001341 horsepower.
- 4Use the reverse-conversion row, 1 horsepower = = 745.699872 watts, as the factor for converting mechanical horsepower back to watts.
Reading your result
The horsepower result row, horsepower = 0.001341, is the converted value for the default input. The forward row, 1 watts = = 0.001341 horsepower, pairs that input with its rounded result. The reverse row, 1 horsepower = = 745.699872 watts, states the watt equivalent of one mechanical horsepower; it is a reference factor, not a second conversion of the entered value. The repeated equals signs in the displayed rows mean a single equality.
Limitations
The conversion assumes mechanical horsepower and uses the factor 745.699872 watts per horsepower. Metric horsepower and other horsepower definitions require different factors. Display rounding means converting a rounded result back may not reproduce the original input exactly. This is a unit conversion, not a motor-efficiency calculation: electrical input watts do not necessarily equal mechanical output watts.
Common questions
Why does the default input of 1 watt produce 0.001341 horsepower?+
One mechanical horsepower equals 745.699872 watts using this calculator's factor. Dividing 1 watt by that factor gives 0.001341 horsepower after rounding to six decimal places.
How do I convert mechanical horsepower back to watts?+
Multiply the horsepower value by 745.699872. The reverse row shows the reference conversion: 1 horsepower = = 745.699872 watts.
Does this calculator convert watts to metric horsepower?+
No. Its factor is for mechanical horsepower. A rating stated in metric horsepower, often labeled PS or CV, needs a different conversion factor.
Can I use a motor's electrical wattage to find its shaft horsepower?+
Not directly. This calculator expresses the entered power in mechanical horsepower units, but it does not account for motor losses. To estimate shaft horsepower from electrical input, first multiply the input watts by the motor's efficiency expressed as a decimal, then convert the resulting output watts.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.