Question 1

What is mechanical horsepower?

Accepted Answer

Mechanical (imperial) horsepower = 745.7 watts. Defined by James Watt: 550 ft-lbf/s or 33,000 ft-lbf/min. Used for car engines, motors, and industrial equipment in US/UK.

Question 2

How does mechanical HP differ from metric HP?

Accepted Answer

Mechanical HP = 745.7 W. Metric HP (PS) = 735.5 W. Mechanical is ~1.4% higher. US/UK use mechanical; continental Europe uses metric PS (Pferdestärke).

Question 3

What's the difference between mechanical and electrical horsepower?

Accepted Answer

Mechanical HP (550 ft·lb/s) = 745.7W. Electrical HP = 746W. Metric HP (PS) = 735.5W. Boiler HP = 9810W. Different industries defined their own standards.

Question 4

How do I size a motor or generator?

Accepted Answer

Calculate peak power needs, add 20-25% safety margin. Consider duty cycle - continuous vs intermittent use affects sizing differently.

Mechanical Horsepower to Watts Converter

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