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Helicopter advance ratio calculator

Advance ratio is a non-dimensional measure of the flow speed relative to a rotor, within the plane of rotation. It's defined as the ratio of the inplane flow speed \(V_{IP}\) to the rotor tip speed \(\Omega R\).

Helicopter Speed

\( KTAS \)

Forward Rotor Tilt

\( deg \)

Pitch, Positive Nose Up

\( deg \)

Main Rotor Radius

\( ft \)

Main Rotor Speed

\( RPM \)

Advance Ratio


\( - \)


This calculator estimates the advance ratio \(\mu \) of a helicopter main rotor in level flight.


The following equation is used to estimate the advance ratio. It assumes the flow speed in the plane of the rotor is \( V \cos (\gamma -\theta )\).

\[ \mu = \frac{V\cos ( \gamma -\theta )}{\Omega R} \]

Many symbols are defined in Helicopter Abbreviations and Symbols. In addition, we use the following symbols here.

\(\gamma \) main rotor forward tilt

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