Public float, also known as free float, is the number of shares of a company's stock that are freely available for trading on the open market. It is calculated by subtracting restricted shares, such as those held by insiders or locked in employee stock ownership plans (ESOPs), from the total number of outstanding shares.

Public float is an important metric for investors to consider when evaluating a stock, as it provides a measure of liquidity. A stock with a high public float is generally easier to buy and sell than a stock with a low public float. This is because there is a larger pool of buyers and sellers for stocks with high public floats.

Stocks with low public floats are more susceptible to volatility, as relatively small transactions can have a large impact on the stock's price. This is because there are fewer shares available to trade, so even a small number of buyers or sellers can move the price significantly.

Public float can also be used to calculate a company's market capitalization, which is the total value of all of its outstanding shares. Market capitalization is calculated by multiplying the public float by the current share price.