How Swing Bowling Works: Conventional and Reverse Swing
How swing bowling works: how seam and shine make the ball curve, the difference between inswing and outswing, and how reverse swing comes about.
Swing bowling is one of the most skilful arts in cricket. A bowler who can make the ball curve through the air gives the batter little time to adjust, and the best swing bowlers can dismiss top batters in a handful of deliveries. The idea sounds simple, but it depends on a delicate balance of aerodynamics, technique and the state of the ball.
The basic idea
A cricket ball swings because air flows differently around its two sides. When one side of the ball is smooth and the other is rough, the airflow around them separates from the surface at different points. This creates a pressure difference that pushes the ball sideways while it is in flight. With a conventional swing, the ball curves towards its rougher side.
Seam position and grip
The seam is the raised line of stitching around the ball, and the bowler uses it to control which way the ball moves. In a typical delivery the seam is held upright and angled slightly, and the bowler keeps the ball’s shiny side facing one way and the rough side the other. The direction of the seam helps start the airflow disturbance on the rough side.
An outswinger is a ball that moves away from a right-handed batter, while an inswinger moves towards them. A right-arm bowler usually bowls the outswinger by angling the seam towards the slips and the inswinger by angling it towards fine leg, and holds the ball so that the shine is on the appropriate side.
Keeping the shine
To make conventional swing work, the fielding side must keep one side of the ball smooth. Players rub the ball on their clothing to polish it, which is allowed, while the other side is left to roughen naturally as the ball hits the pitch and boundary. Using saliva has been prohibited in international cricket since 2022, so sweat is the main aid. Altering the ball’s condition by other means is ball tampering.
Conditions that help
Bowlers often talk about overcast skies and humid air helping the ball swing, and many believe a new ball moves most in the first few overs. The scientific evidence about the effect of atmospheric conditions is mixed, however, and the state of the ball and the bowler’s action remain more important. Pace also matters, as a ball that is bowled too slowly or too quickly may not swing at its best.
Reverse swing
Reverse swing is the opposite of conventional swing. When a ball is old and one side has become very rough while the other remains smooth, a fast bowler can make it curve towards the smooth side instead of the rough one. It usually appears when the ball is no longer new, which makes it a valuable weapon in the middle of a long innings.
Reverse swing is closely associated with Pakistan’s fast bowlers. Sarfraz Nawaz is often credited with pioneering it, and Imran Khan, Wasim Akram and Waqar Younis later became its most celebrated exponents. Their ability to curve an old ball late at high speed contributed to some famous victories.
Seam movement
Movement off the pitch is a separate skill from swing. Seam movement happens when the ball lands on its seam and deviates after bouncing, and the best seam bowlers can combine it with swing for greater effect. Some bowlers also use a wobble seam grip, which causes the ball to move unpredictably off the surface.
Defending against swing
Batters play swing by watching the ball closely out of the hand, playing it late and close to the body, and leaving deliveries that move away from them outside off stump. Against a new ball the best approach is often patience.
A skill of technique
Swing bowling relies on a smooth, balanced action and a consistent wrist position at release. Bowlers who learn to control it can use the new ball as a potent weapon, and this explains why swing bowlers such as those from England and Pakistan have been so influential in cricket’s history.
Frequently asked questions
Which way does a cricket ball swing?
With conventional swing, the ball curves towards its rougher side. With reverse swing, an old ball curves towards its smoother side.
What is reverse swing?
It is swing in the opposite direction to the normal one, usually achieved by fast bowlers with an older ball that has one very rough side.
Is it legal to polish the ball?
Yes, a fielder may polish the ball with sweat, but using saliva has been banned in international cricket since 2022, and altering the ball by other means is ball tampering.