CdA is the product of the drag coefficient (Cd) and frontal area (A). It represents your total aerodynamic drag profile and is measured in m². Lower is more aerodynamic.

How do I get accurate CdA data?

Use a flat, windless course. Record power and speed with a power meter and GPS. Average over multiple laps to reduce wind effects. This calculator then estimates CdA from those averages.

What CdA values are typical?

Hoods position: 0.35-0.40 m². Drops: 0.30-0.35 m². TT position: 0.22-0.28 m². Professional TT riders: 0.20-0.22 m².

How much speed does a lower CdA give?

At 40 km/h, reducing CdA by 0.01 m² saves about 2-3W and gains roughly 0.1-0.2 km/h. At higher speeds the gains are larger.

BikeCalcs

CdA Calculator — Estimate Drag Coefficient Area

Estimate your drag coefficient area from field test data.

Average Power

Average Speed

Total Weight (rider + bike)

Crr

Road tyre ~0.005

Gradient

Use 0 for flat course

Air Density

How We Calculate This

CdA Estimation

By rearranging the power equation:

P_aero = P_total - P_rolling - P_gravity
CdA = 2 x P_aero / (air_density x v³)

This assumes steady-state conditions with accurate power and speed data.

Frequently Asked Questions

Related Calculators

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Drag Calculator

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Wind Resistance Calculator

Calculate the effect of headwind and tailwind on power requirements.

Last updated: February 2026

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.