HP to ft-lb/min Calculator
Convert horsepower to foot-pounds per minute (the original definition of HP).
This converter shows horsepower in foot-pounds per minute — the exact unit James Watt used when he defined one horsepower as 33,000 foot-pounds of work per minute.
HP to ft-lb/min Formula
This is where horsepower comes from. Watt measured that a horse could do roughly 33,000 foot-pounds of work each minute, and that figure became the definition of one horsepower — which is also why the constant 5252 (33,000 ÷ 2π) appears in the torque formula.
How to Use This Calculator
- Enter horsepower.
- Read ft-lb/min, with ft-lb/sec also shown.
Worked Example
The Origin of Horsepower
In the 1780s James Watt needed a way to market his steam engines against the draft horses they replaced. He measured that a strong horse could do about 33,000 foot-pounds of work per minute — lifting 33,000 pounds one foot, or 330 pounds 100 feet, in sixty seconds — and named that rate one horsepower. Every modern horsepower figure still traces back to this benchmark, which is why the unit feels arbitrary until you see its origin.
Why 33,000 Leads to 5252
This definition is the source of the famous 5252 constant in the torque equation. Since power = torque × angular velocity, and one revolution is 2π radians, dividing 33,000 by 2π gives 5,252 — the RPM at which horsepower and torque are numerically equal. The same 33,000 ft-lb/min also equals 550 ft-lb/sec and 745.7 watts.
HP to ft-lb/min and ft-lb/sec
| Horsepower | ft-lb/min | ft-lb/sec |
|---|---|---|
| 1 | 33,000 | 550 |
| 2 | 66,000 | 1,100 |
| 5 | 165,000 | 2,750 |
| 10 | 330,000 | 5,500 |
Frequently Asked Questions
One horsepower equals 33,000 foot-pounds per minute, or 550 foot-pounds per second. This is the original definition by James Watt.
James Watt estimated a strong draft horse could do about 33,000 foot-pounds of work per minute, and used that as one horsepower to rate his steam engines.
The 5252 in the torque formula equals 33,000 ÷ 2π. Both trace back to the same 33,000 ft-lb/min definition of horsepower.
Multiply horsepower by 550, since 33,000 per minute divided by 60 seconds equals 550 per second.
A foot-pound is a unit of work (or energy) — one pound of force acting through one foot. Foot-pounds per minute is therefore a unit of power.