Calculate horsepower from quarter mile times, trap speed, or torque. Estimate performance metrics and power-to-weight ratios.
Horsepower
1879 HP
320 lb-ft torque
Horsepower
1879
HP
Torque
320
lb-ft
1/4 Mile
13.50
seconds
Trap Speed
578
mph
Power-to-Weight
1074 HP/ton
Est. 0-60 mph
3.4 sec
HP per lb
0.537
HP = (Weight / ET³) × 1320.61
Buschur formula
HP = Weight × (Speed / 234)³
HP = (Torque × RPM) / 5252
HP and Torque cross at 5252 RPM
HP/ton = (HP / Weight) × 2000
| Class | HP Range | HP/Ton | 1/4 Mile | 0-60 mph |
|---|---|---|---|---|
| Economy | 100-150 | 50-80 | 17-19s | 10-13s |
| Family Sedan | 150-250 | 80-120 | 15-17s | 7-10s |
| Sports Car | 250-400 | 150-250 | 13-15s | 5-7s |
| Muscle Car | 400-600 | 200-300 | 12-13s | 4-5s |
| Supercar | 600-800 | 300-400 | 10-12s | 3-4s |
| Hypercar | 800+ | 400+ | <10s | <3s |
1 HP (mechanical)
= 745.7 Watts
1 HP (metric/PS)
= 735.5 Watts
1 kW
= 1.341 HP
1 lb-ft
= 1.356 Nm
Horsepower = (Torque x RPM) / 5252. This formula uses torque in lb-ft. Example: 300 lb-ft at 4000 RPM = (300 x 4000) / 5252 = 228 HP. Conversions: 1 HP = 0.746 kW = 1.014 PS (metric HP). Peak HP and peak torque occur at different RPMs; they cross at 5252 RPM.
Horsepower (HP) measures the rate at which work is done. One mechanical horsepower equals 550 foot-pounds per second or 745.7 watts. In cars, it determines how fast the engine can move the vehicle, affecting acceleration and top speed.
Torque is rotational force (measured in lb-ft or Nm), while HP is the rate of applying that force. HP = (Torque × RPM) / 5252. Torque provides initial acceleration; HP maintains speed. "Torque wins races, HP sells cars."
Crank HP (gross) is measured at the engine crankshaft. Wheel HP (WHP) is measured at the wheels after drivetrain losses. Typically WHP is 15-20% less due to transmission and differential friction. Dyno numbers are usually WHP.
Use the formula: ET = (Weight/HP)^(1/3) × constant. Weight should include driver. Actual times vary with traction, altitude, temperature, and driver skill. Professional times use weight with driver and half tank of fuel.
Economy cars: 50-80 HP/ton. Sports cars: 150-250 HP/ton. Performance cars: 250-400 HP/ton. Supercars: 400+ HP/ton. Formula 1: ~1000 HP/ton. Higher ratios mean faster acceleration.
Horsepower
1879 HP
320 lb-ft torque