Swing refers to the fluctuation in a player's stack or bankroll. In both cases swing is seen as a deviation from the mean value, whereby a small swing is a small deviation and a large swing is a large deviation. Though exact numbers can be calculated, swing is most commonly used as an abstract term.

Swing is not a good indicator of the ability of a player. Certain strategies, like being loose aggressive, entail a large amount of deviation but can be employed effectively. Equally so an extremely tight and timid player may have virtually no swing, but have a gradual decline in their stack/bankroll.