Stall Speed Calculator

Work out stall speed instantly with clear inputs, formula shown and shareable results.

About Stall Speed Calculator

Stall speed comes from setting lift equal to weight at the maximum lift coefficient: V equals the square root of 2W divided by rho, wing area and CLmax. It therefore rises with the square root of weight and falls as CLmax increases when flaps are extended.

Formula

Stall speed

Vs = sqrt(2 x W x g / (rho x S x CLmax))

Worked example

With the default values below, Stall Speed Calculator returns Stall speed of 48.31. Change any input above and every figure here is recalculated in your browser.

Inputs used

Aircraft weight: 1,000 kg
Wing area: 16.2 m²
Maximum lift coefficient: 1.6
Air density ratio (sigma): 1 x

Results

Stall speed: 48.31 kt
Stall speed: 24.85 m/s
Wing loading: 61.73 kg/m²
Typical approach speed (1.3 Vs): 62.81 kt

Step by step

1Values used
2Stall speed
3Stall speed= 48.31 kt
4Stall speed= 24.85 m/s
5Wing loading= 61.73 kg/m²
6Typical approach speed (1.3 Vs)= 62.81 kt

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

How much does weight change stall speed?

By the square root of the weight ratio. A 10% heavier aircraft stalls about 5% faster.

Why is approach speed 1.3 times stall speed?

It is the certification-based margin (Vref = 1.3 Vso) that keeps enough manoeuvre and gust margin during the approach and flare.