This hp to whp calculator use WHP = Engine HP × (1 – (Drivetrain Loss / 100)) formula to measure the actual power output delivered to the wheels of a vehicle.
Engine horsepower (HP) represents the raw power generated by the engine, wheel horsepower (WHP) indicates the usable power that reaches the wheels after accounting for various power losses through the drivetrain system.
- 220 HP → 184.8 WHP (16% loss)
- 275 HP → 230 WHP (16% loss)
- 325 HP → 273 WHP (16% loss)
- 375 HP → 315 WHP (16% loss)
- 425 HP → 357 WHP (16% loss)
- 475 HP → 399 WHP (16% loss)
HP to WHP Calculator
| Engine HP | Drivetrain Type | Loss Factor | Resulting WHP |
|---|---|---|---|
| 250 | FWD | 15% | 212.5 |
| 300 | FWD | 15% | 255 |
| 350 | FWD | 15% | 297.5 |
| 400 | FWD | 15% | 340 |
| 450 | FWD | 15% | 382.5 |
| 500 | FWD | 15% | 425 |
| 300 | RWD | 17% | 249 |
| 400 | RWD | 17% | 332 |
| 500 | RWD | 17% | 415 |
| 600 | RWD | 17% | 498 |
| 700 | RWD | 16% | 588 |
| 800 | RWD | 16% | 672 |
| 900 | RWD | 16% | 756 |
| 250 | AWD | 22% | 195 |
| 300 | AWD | 22% | 234 |
| 400 | AWD | 22% | 312 |
| 500 | AWD | 22% | 390 |
| 600 | AWD | 22% | 468 |
| 700 | AWD | 22% | 546 |
HP to WHP Conversion Formula
The formula for converting HP to WHP accounts for drivetrain losses using a drivetrain loss factor.
WHP = HP × (1 - Drivetrain Loss Factor)Typical drivetrain loss factors:
- Front-Wheel Drive (FWD): 15-20% loss (multiply by 0.85-0.80)
- Rear-Wheel Drive (RWD): 15-20% loss (multiply by 0.85-0.80)
- All-Wheel Drive (AWD): 20-25% loss (multiply by 0.80-0.75)
Calculating WHP for a 300 HP RWD vehicle with 15% drivetrain loss:
WHP = 300 × (1 - 0.15)
WHP = 300 × 0.85
WHP = 255How to Convert HP to WHP?
To convert HP to WHP, you need to account for these losses, which vary based on the drivetrain type:
For Manual Transmission:
- Front-wheel drive (FWD): Multiply HP by 0.85 (15% loss)
- Rear-wheel drive (RWD): Multiply HP by 0.83 (17% loss)
- All-wheel drive (AWD): Multiply HP by 0.80 (20% loss)
For Automatic Transmission:
- FWD: Multiply HP by 0.83 (17% loss)
- RWD: Multiply HP by 0.80 (20% loss)
- AWD: Multiply HP by 0.75 (25% loss)
If you have a manual RWD car with 300 HP: WHP = 300 × 0.83 = 249 WHP
Calculation for a 500 HP AWD vehicle with 22% drivetrain loss:
WHP = 500 × (1 - 0.22)
WHP = 500 × 0.78
WHP = 390How Much HP is 320 WHP?
HP = WHP ÷ (1 - Drivetrain Loss Factor)For 320 WHP with a typical RWD drivetrain loss of 17%:
HP = 320 ÷ (1 - 0.17)
HP = 320 ÷ 0.83
HP = 385.54 HPHow Much Crank HP is 300 WHP?
For 300 WHP, assuming an FWD vehicle with an 18% drivetrain loss:
Crank HP = 300 ÷ (1 - 0.18)
Crank HP = 300 ÷ 0.82
Crank HP = 365.85 HPCrank horsepower (measured at the engine’s crankshaft) to WHP conversion follows the same principle.
How Much Less is WHP to HP?
Here’s a typical breakdown:
- FWD vehicles: 15-20% less WHP than HP
- RWD vehicles: 15-20% less WHP than HP
- AWD vehicles: 20-25% less WHP than HP
For example, a 400 HP AWD vehicle might produce:
WHP = 400 × (1 - 0.23)
WHP = 400 × 0.77
WHP = 308 WHP
Difference = 92 HP (**23% loss**)
Sources and References
- Society of Automotive Engineers (SAE): https://www.sae.org/standards/
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