Aerodynamic Horsepower Calculator
Calculate aerodynamic drag force and horsepower required to overcome wind resistance at target speeds. Optimize coefficient of drag (Cd) and frontal area (A).
Aerodynamic Horsepower Calculator
Calculate exact aerodynamic drag horsepower, rolling resistance HP, grade HP, and total engine power required to overcome air resistance at any target velocity.
Table of Contents
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Enter Vehicle & Condition Parameters
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Aerodynamic Horsepower Calculator Results
The Formula (How It Works)
Aerodynamic drag force grows with the square of speed, so the horsepower needed to overcome it grows with the cube of speed. Doubling your speed takes roughly eight times the aero horsepower.
F_drag (lbf) = 0.5 × ρ × Cd × A × V²
HP_aero = (F_drag × V) ÷ 550
F_roll (lbf) = Crr × Weight × cos(θ)
HP_roll = (F_roll × V) ÷ 550
HP_engine = (HP_aero + HP_roll + HP_grade) ÷ (1 − drivetrain loss)
- ρ — air density in slugs/ft³, computed from your temperature, barometric pressure and elevation using the ideal gas law.
- V — speed in feet per second (mph × 1.46667). Headwind is added to the airspeed used for drag only.
- 550 — foot-pounds per second in one mechanical horsepower.
Typical Cd & Frontal Area Values
| Vehicle Type | Cd | Frontal Area | Weight | Crr |
|---|
No spec sheet? Estimate frontal area as height × width × 0.85 (in feet). Typical Crr is 0.010–0.015 for street tires on asphalt.
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