What is the horsepower formula?

HP = Torque (lb-ft) × RPM / 5252. The 5252 constant comes from the definition of horsepower (33,000 ft-lbs per minute) divided by 2π. Example: 300 lb-ft at 4,000 RPM = 300 × 4,000 / 5252 = 228.5 HP. Peak torque and peak horsepower occur at different RPMs — they cross exactly at 5,252 RPM.

What is the difference between HP and torque?

Torque is the twisting force (in lb-ft or N-m) — it's what accelerates you from rest. Horsepower is torque × RPM — it's what sustains speed. High torque at low RPM (diesels, electric motors): great for towing, quick off-the-line feel. High HP at high RPM (sports cars): great for top speed. Both matter for driving experience.