Loading calculator…
Calculate horsepower four ways at once — torque × RPM, 1/4-mile ET, trap speed and 0–60 time — plus SAE weather correction, before/after mod gains, wheel ↔ crank conversion and power-to-weight.
This usually points to launch, gearing or traction — not necessarily wrong horsepower. Trap speed is the least launch-sensitive of the three. The numbers above are not altered.
Illustrative curve shaped through your entered torque at 5000 RPM. HP and torque (lb-ft) always cross at 5,252 RPM. Real dyno curves vary by engine.
Four methods, all live. Torque: HP = torque × RPM ÷ 5,252. Fox/Roger ET: HP = weight ÷ (ET/5.825)³. Huntington trap: HP = weight × (trap/234)³. 0–60: HP = weight ÷ (time/0.76)^1.25. kW = HP × 0.7457; PS = HP × 745.7 ÷ 735.5.
Torque vs horsepower. Torque is twisting force; horsepower is how fast that work is done. "Torque wins races" off the line, horsepower wins at the top end — and the two curves always cross at 5,252 RPM.
Wheel vs crank. Crank HP = wheel HP ÷ (1 − loss); wheel HP = crank HP × (1 − loss). Loss percentages are estimates.
Correction. SAE factor uses dry pressure and air temperature; the altitude option applies a flat 3% per 1,000 ft for naturally aspirated engines. Δ-HP subtracts the before-mod estimate from the after-mod estimate at the same weight.
The dyno curve is a modeled illustration through your entered point, not a measured curve. No live weather or dyno data is fetched.
If you know dyno torque at a given RPM, torque × RPM is exact. The ET, trap and 0–60 methods are estimates for track-tested cars — typically within ±3–5% on a well-prepped track. Trap speed is the most reliable of those because it's least affected by launch.
HP = torque × RPM ÷ 5,252, so at exactly 5,252 RPM horsepower equals torque (in lb-ft). Below it torque is the larger number, above it horsepower is. Every dyno chart crosses there.
For a typical passenger car, 250–350 lb-ft feels strong; trucks and performance cars often exceed 400. What matters is torque relative to weight and gearing — check the power-to-weight figures.
On good track prep, ET formulas land within about 3–5% of crank HP. Poor launches, wheelspin or bad shifts inflate ET and make the estimate read low.
Power is lost to the transmission, driveshaft, differential and tires before it reaches the ground. Typical losses: FWD ~10%, RWD manual ~15%, RWD auto ~17%, AWD ~20%, but real cars range 10–25%.
It normalizes a dyno result to standard conditions (25 °C, 990 hPa dry air) so runs on hot, high or humid days can be compared fairly. CF = 1.18 × (990/Pd) × √((T+273)/298) − 0.18.
Yes — naturally aspirated engines lose roughly 3% per 1,000 ft. Turbocharged engines lose much less. Use the altitude-only option if you don't have pressure and temperature readings.
PS (Pferdestärke) is metric horsepower: 735.5 W, versus 745.7 W for a mechanical horsepower. 1 hp ≈ 1.014 PS.
Results are estimates for educational purposes only and are not financial advice. Verify with a qualified professional before making decisions.
Last updated October 2026