Snooker Angles Explained: Cut Angles, Half-Ball and Throw
Published · Mark O'Sullivan
A cut angle is simply the angle between the line the cue ball travels and the line the object ball needs to take into the pocket, and you judge it by standing behind the cue ball and sighting where that angle opens up.
Every pot you play, from a straight blue down the rail to a thin safety off the black, is really the same bit of geometry repeated with a different angle. Once you can see that angle rather than guess at it, potting stops feeling like luck and starts feeling like measurement. This piece works through the basic vocabulary — cut angle, half-ball, tangent line, throw and cushion reflection — without any formulas, because none of it needs maths to be useful at the table.
What it does need is a way of seeing the angle before you get down on the shot, and a bit of practice trusting what you see. The rest of this article builds that picture step by step, starting with how to read an angle in the first place.
Reading a cut angle from behind the cue ball
Stand behind the cue ball, in line with where you intend to strike it, and look through to the object ball and on to the pocket. You are looking for two lines: the line from the cue ball to the object ball, and the line from the object ball to the pocket. The angle between those two lines, measured at the object ball, is the cut angle. A dead straight pot has no angle at all — the two lines sit on top of each other. As the pocket moves further round the side of the object ball relative to the cue ball, the angle opens up. This sounds obvious written down, but most players never actually do it. They get down on the shot, look at the pot, and adjust by feel. That works fine for shots you have played a thousand times, but it falls apart on anything unfamiliar. Standing behind the cue ball first, even for half a second, trains your eye to see the angle as a shape rather than a guess, and that shape is what tells you where on the object ball you need to aim.
The half-ball contact: the reference shot
The half-ball shot is the one every coach starts with, and for good reason. It is the contact where the cue ball strikes the object ball exactly on its centre line as seen from behind — half of the object ball is covered by the cue ball's path, half is showing. That contact produces a cut angle of roughly 30 degrees, and it sits neatly in the middle of the range of angles you will actually meet on a table. The reason it works as a reference is not that 30 degrees is common — plenty of shots are steeper or finer — but that it is the easiest angle to picture accurately. Full-ball and near-full-ball contacts are easy because there is almost no angle to misjudge. Very thin contacts are hard because a small error in aim causes a huge error in direction. The half-ball sits between those extremes, easy enough to see clearly but sharp enough to be a genuine test of your eye. Once you can find a half-ball contact reliably, you have a fixed point either side of which you can judge fuller or thinner contacts by comparison, rather than trying to work out every angle from nothing. The table below gives rough contacts and the cut angles they produce, along with the sort of situation each one tends to come up in.
| Contact | Approximate cut angle | Typical use |
|---|---|---|
| Full ball | 0 degrees | Straight pot, often played with stun for position |
| Three-quarter ball | Around 15 degrees | Gentle angle, short to mid-range cut |
| Half ball | Around 30 degrees | The reference shot, mid-range cut |
| Quarter ball | Around 45 degrees | Thinner cut, common on long positional shots |
| Thin or edge contact | 60 degrees or more | Very fine cut, often used to escape or play safe |
The tangent line: where the cue ball goes after contact
Once you have found your contact point, the next question is what happens to the cue ball after impact, and that is governed by the tangent line. With a plain-ball hit — no side, and the cue ball neither rolling forward heavily nor screwing back at the moment of contact — the cue ball leaves along a line that runs roughly at right angles to the direction the object ball takes. This is the tangent line, and it is the single most useful piece of geometry in the game for working out position. If you play a half-ball cut with a plain stun-like contact, the object ball goes off at its 30-degree angle and the cue ball peels away along the tangent, close to 90 degrees from that. Knowing this lets you predict roughly where the cue ball will finish before you have even hit the shot, which is the whole basis of positional play. Add topspin and the cue ball will drift forward off that tangent line as it rolls on; add backspin and it will hang back or draw away from it. But the tangent line itself, based on the cut angle and a truly plain hit, is the starting point every player learns to picture first.
Throw: how side and friction shift the object ball
The diagram version of a shot assumes the object ball travels exactly along the line from the centre of the cue ball through the centre of the object ball at the moment of contact. In practice it does not, quite. There is a brief moment of contact between the two balls where friction acts, and that friction nudges the object ball very slightly off that pure line. This effect is called throw, and it is most noticeable on slower shots and on shots played with side. Plain running or check side on the cue ball increases throw because the ball's surface is gripping and skidding against the object ball in a way that drags the object ball's path with it. The effect is small — a fraction of a degree on most shots — but on a fine cut over any distance, a fraction of a degree is the difference between a clean pot and a ball that clips the jaw and sits up. The practical allowance most players learn by feel is to aim very slightly fuller than the pure geometry suggests whenever side is applied, and to expect more throw the slower the cue ball is travelling, since a slower ball spends longer in contact and the friction has more time to act. There is no need to calculate this; you learn the adjustment the same way you learn anything else at the table, by playing the shot, watching where it goes, and correcting next time.
Using cushions: reflection, pace, side and worn cloth
The basic rule for a ball coming off a cushion with no side applied is the same one light follows off a mirror: the angle the ball arrives at roughly equals the angle it leaves at, measured against the cushion. This is useful for working out escape routes on safety shots and for planning position off the side rail, and it is close enough to true on a plain ball at moderate pace to be worth relying on.
Pace and side change the rebound
That rule bends under two conditions. Heavy pace tends to straighten the rebound angle slightly, because the ball is compressing the cushion rubber more and spending less relative time gripping it, so it comes off flatter than expected. Side spin changes the rebound angle more noticeably: side applied before the cushion contact will hold or widen the angle depending on which way it is running relative to the cushion, which is exactly why players use side deliberately to steer the cue ball round the table rather than relying on the natural angle alone.
Cloth condition matters more than most players allow for
A worn cloth, or one that has gone slightly napped and shiny along a well-used cushion line, will not reflect the ball as cleanly as fresh cloth. Rebounds tend to come off shorter and less predictably on tired cushions, and club players who play mainly on one table often build an unconscious feel for that table's particular quirks without realising it — which is also why the same shot can feel completely different on an unfamiliar table. There is no fixed correction for this beyond playing a few cushion shots before a match to feel how the table is behaving that day.
Learning angles by feel: the same shot from three positions
The quickest way to build real judgement of cut angles is not to study diagrams but to play the same pot repeatedly from different positions and watch what changes. Set up a simple pot into a middle pocket and play it from three cue ball positions: one giving a thin cut, one a half-ball, and one closer to full ball. Play each one several times, watching where your eye was looking from behind the cue ball before you got down, and comparing that picture to where the ball actually went. A useful trick here is to mark the pocket, or the point on the cushion you are using as a reference, with a small dab of chalk on the rail rather than the cloth. It gives you a fixed visual target to line up against when you stand behind the cue ball, and because it is on the cushion rather than the baize it does not affect the roll of the ball. Doing this across a session, moving the cue ball a little further round each time, trains your eye to recognise angles as pictures rather than numbers, which is exactly how the pros read a table — not by measuring anything, but by pattern recognition built up over thousands of repetitions.
A short practice routine
A simple fifteen-minute routine, done regularly, does more for your angle judgement than an hour of random potting. Set a single object ball near a centre pocket and play it from five cue ball positions arranged in a fan, moving from a straight pot through to a fine cut. Play each position three times before moving to the next, and force yourself to stand behind the cue ball each time and name the contact — full, three-quarter, half, quarter, thin — before getting down on the shot. Once that feels comfortable, repeat the same fan into a corner pocket, since corner angles behave slightly differently to centre pockets and are worth training separately. Finish with a few cushion shots off a single object ball, using the rail-chalk trick to check whether your read of the rebound angle matches reality. None of this needs a partner or a full table free — a spare twenty minutes before a club night is enough to keep the eye sharp.
Frequently asked questions
What exactly is a cut angle in snooker?
A cut angle is the angle between the path the cue ball travels to reach the object ball and the path the object ball must then take to reach the pocket. It is measured at the object ball, and the wider the angle, the finer the required contact.
Why is the half-ball shot used as a teaching reference?
The half-ball contact produces a cut angle of roughly 30 degrees, which sits in the middle of the range players actually meet at the table. It is easier to judge accurately than very full or very thin contacts, so it gives a fixed point to compare other angles against.
What is the tangent line and why does it matter?
The tangent line is the direction the cue ball tends to travel after a plain-ball contact, running roughly at right angles to the object ball's path. It matters because it lets a player predict where the cue ball will finish, which is the basis of positional play.
What causes throw on the object ball?
Throw is caused by friction between the two balls during the brief moment of contact, which nudges the object ball slightly off the pure geometric line. It is more pronounced on slower shots and when side is applied to the cue ball, so a slightly fuller aim is often needed in those situations.
Does side spin always widen the cushion rebound angle?
Not always — it depends on which way the side is running relative to the cushion, and it can hold the angle tighter as well as widen it. This is why players use side deliberately to steer the cue ball around the table rather than relying on the natural rebound alone.
Why does the same shot feel different on cushions with worn cloth?
Worn or shiny cloth along a well-used cushion line does not grip and release the ball as cleanly as fresh cloth, so rebounds tend to come off shorter and less predictably. Playing a few cushion shots before a match helps build a feel for how a particular table is behaving that day.
How can I practise judging cut angles without a coach?
Set up one pot and play it repeatedly from several cue ball positions, standing behind the cue ball each time to name the contact before getting down on the shot. Marking a reference point on the cushion with chalk gives you a fixed target and helps train your eye to recognise angles as pictures rather than guesses.
Is a fuller aim always the right way to allow for throw?
A slightly fuller aim is the usual allowance when playing with side or at slower pace, since throw tends to push the object ball away from the pure geometric line in those conditions. It is a small adjustment learned by feel and observation rather than a fixed rule to apply on every shot.