What is 1 horsepower in ft-lb per second?

1 horsepower equals 550 ft-lb/s and 33,000 ft-lb/min.

Ft Lbs to HP Calculator (Torque & Work to Horsepower)

How to Convert Ft Lbs to HP Correctly

People often search for a “ft lbs to hp calculator” when they want to understand engine output, motor performance, or equipment power requirements. The key is that foot-pounds (ft-lb) and horsepower (HP) are not always direct one-step conversions. In practice, you convert using either rotational speed (RPM) or elapsed time.

If you have torque in foot-pounds and rotational speed in RPM, horsepower is found with the classic formula used in automotive and mechanical engineering:

HP = (Torque × RPM) / 5252

If you instead have total work in foot-pounds and a time duration, horsepower is based on power over time:

HP = (ft-lb per minute) / 33,000

What Ft-Lb Means vs What HP Means

Foot-pound (ft-lb) can represent either torque or work, depending on context:

Torque: Turning force around a shaft, common for engines and motors.
Work: Energy transfer, such as lifting a load through a distance.

Horsepower (HP) is a unit of power, meaning how quickly work is done. Power always includes a time component. That is why conversion from foot-pounds to horsepower requires either RPM (for rotating systems) or time (for linear work calculations).

Torque + RPM to Horsepower (Most Common)

For engines, dyno charts, drivetrains, and rotating machinery, use:

HP = (Torque (ft-lb) × RPM) ÷ 5252

The constant 5252 comes from unit relationships between radians, minutes, and horsepower definitions. A useful rule: on a torque-horsepower graph using ft-lb and HP, torque and horsepower curves cross at 5252 RPM.

Example 1

An engine makes 320 ft-lb at 4,000 RPM:

HP = (320 × 4000) ÷ 5252 = 243.7 HP

Example 2

A machine produces 150 ft-lb at 1,800 RPM:

HP = (150 × 1800) ÷ 5252 = 51.4 HP

Foot-Pounds of Work + Time to Horsepower

If you are measuring actual work (not rotational torque), use time conversion:

1 horsepower = 33,000 ft-lb/min
1 horsepower = 550 ft-lb/s

So, if work is entered in ft-lb and time is in seconds:

HP = (Work ÷ Time in seconds) ÷ 550

If time is in minutes:

HP = (Work ÷ Time in minutes) ÷ 33,000

Example 3

33,000 ft-lb performed in 1 minute:

HP = 33,000 ÷ 33,000 = 1 HP

Example 4

16,500 ft-lb in 30 seconds:

Power = 16,500 ÷ 30 = 550 ft-lb/s → HP = 550 ÷ 550 = 1 HP

Quick Reference Table: Torque and RPM to HP

Torque (ft-lb)	RPM	Horsepower (HP)
100	2000	38.1
150	3000	85.7
200	4000	152.3
250	5000	238.0
300	6000	342.7

Why This Conversion Matters

Understanding ft lbs to hp helps with practical decisions in automotive tuning, industrial motor sizing, pumps, compressors, agricultural machinery, and marine applications. Torque indicates force potential, while horsepower indicates the rate of doing work. Together, they describe performance in real-world operation.

Automotive and Racing

Drivers often compare peak torque and peak horsepower values. The engine’s character depends on where torque is produced in the RPM range, while horsepower influences top-end acceleration and sustained high-speed performance.

Industrial Equipment

In equipment design, engineers may estimate torque load at operating RPM and convert to HP to select a motor with adequate margin. Correct conversion reduces overheating, inefficiency, and premature wear.

Pumps and Compressors

Mechanical load from fluid handling often maps to shaft torque and speed. Converting to HP allows quick comparison to motor nameplate ratings and available electrical supply capacities.

Common Conversion Mistakes to Avoid

Mixing torque and work: ft-lb can describe both; context decides formula.
Ignoring RPM: Torque alone does not equal horsepower.
Using wrong time units: Convert seconds, minutes, or hours correctly before applying constants.
Confusing lb-ft and ft-lb notation: In many settings they are used interchangeably, but keep unit context clear.
Rounding too early: Keep extra decimals in intermediate steps for better accuracy.

Reverse Calculation: HP to Torque

If horsepower is known and you need torque at a specific RPM:

Torque (ft-lb) = (HP × 5252) ÷ RPM

This is useful when reading motor power curves or estimating drivetrain load limits.

Practical Tips for Better Accuracy

Use measured RPM under real load, not just no-load speed.
Account for drivetrain losses if estimating wheel output from crank output.
For electric motors, verify continuous vs peak power ratings.
When possible, validate results with manufacturer charts or dyno data.

FAQ: Ft Lbs to HP Calculator

Not by itself. Horsepower is a rate, so you need speed (RPM) for rotational systems or time for work-based systems.

It is a constant derived from unit conversions linking torque in ft-lb, rotational speed in RPM, and horsepower definitions.

1 HP equals 550 ft-lb/s (and 33,000 ft-lb/min).

In many practical contexts, yes. Both are used for torque notation, though consistency in technical documents is recommended.

At 5252 RPM, torque in ft-lb and horsepower have the same numeric value.

Final Takeaway

A reliable ft lbs to hp calculator should support both major scenarios: torque plus RPM for engines and rotating shafts, and foot-pounds over time for work-rate problems. Use the calculator above to get fast, accurate values and to reverse-calculate torque when horsepower is known.