Kilowatt to Foot-pound per Second Converter

How do I convert ft⋅lbf/s to horsepower?

Formula: hp = ft⋅lbf/s ÷ 550

Examples:

• 550 ft⋅lbf/s = 1 hp (exact definition)
• 1,100 ft⋅lbf/s = 2 hp
• 275 ft⋅lbf/s = 0.5 hp
• 5,500 ft⋅lbf/s = 10 hp

ft⋅lbf/s to HP converter →

How do I convert ft⋅lbf/s to watts?

Formula: W = ft⋅lbf/s × 1.356

Examples:

• 100 ft⋅lbf/s = 135.6 W
• 550 ft⋅lbf/s = 746 W (1 hp)
• 1,000 ft⋅lbf/s = 1,356 W = 1.356 kW

ft⋅lbf/s to Watts converter →

Why is 1 hp = 550 ft⋅lbf/s?

Historical origin: James Watt (1780s) measured draft horses' work capacity

Experiment: Horse lifting coal from mine

• Typical horse: Lifted ~22,000 lb⋅ft per minute
• Watt's marketing: Rated engines at 33,000 lb⋅ft/min (50% safety margin)
• Conversion: 33,000 ft⋅lbf/min ÷ 60 = 550 ft⋅lbf/s = 1 hp

Modern equivalent: 1 hp = 745.7 W = 0.746 kW

Persists: Still used for engines despite metric system adoption.

How do I calculate power from force and velocity?

Formula: Power (ft⋅lbf/s) = Force (lbf) × Velocity (ft/s)

Examples:

• Towing 1,000 lb at 10 ft/s: 10,000 ft⋅lbf/s = 18.2 hp = 13.6 kW
• Lifting 500 lb at 2 ft/s: 1,000 ft⋅lbf/s = 1.82 hp = 1.36 kW
• Pushing 200 lb at 5 ft/s: 1,000 ft⋅lbf/s = 1.82 hp

SI equivalent: Power (W) = Force (N) × Velocity (m/s)