You are snookered: a ball you may not hit sits between the white and every ball you may hit. This lesson covers what counts as a snooker, what the rules say about fouls and misses, the mirror aim off one cushion (對射角), choosing a route by its room, how pace moves the aim, where the balls end afterwards, escapes off two and three cushions, and swerving round the blocking ball.

Series map. ★ Basics: 01 Cue action and elevation → 02 Aiming and potting → 03 Tip and power → 04 Where the white goes · ★★ Club: 05 Side spin → 06 Cut and side into pockets → 07 Cushions → 08 Doubles · ★★★ Advanced: 09 Escaping snookers (this post) → 10 Multi-ball shots → 11 Safety → 12 Position play · ★★★★ Hard: 13 Break-building → 14 Special shots · Reference: 15 Rules, tactics and practice · ★★★★★ Pro: 16 Cue-ball control.

Learning Outcome

  • Tell whether you are snookered, and know the foul, miss and free-ball rules.
  • Aim a one-cushion escape at the mirror ball.
  • Choose a route by its room, and adjust the aim for pace.
  • Think about where the white and the red end.
  • Aim a two-cushion escape with the double mirror.
  • Know when a swerve is the way out, and how the cue is raised for it.

Chapter 1 — Snookered

1 · The view down the cue

View down the cue from behind the white. The blue ball sits straight ahead and the red is hidden behind it; only the top of the red shows over the blue

Red is the ball on, and it is straight behind the blue. Hitting the blue first is a foul. You need a way round.

2 · Snookered or not? Look at both edges

Three small top views of the white, a blue and a red. Two shaded lanes show the white's path to just touch each edge of the red. 1: the blue blocks both lanes: snookered. 2: the blue blocks one lane: still snookered. 3: both lanes are clear: not snookered

The rule: you are not snookered if the white can travel straight to both edges of at least one ball on.

Left edge Right edge
1 blocked blocked snookered
2 clear blocked still snookered
3 clear clear not snookered

When two balls are in the way, the one nearer the white is the snookering ball. A cushion never snookers you.

3 · Fouls, the miss and the free ball

Five rows, each a rule about hitting the ball on: foul, foul and a miss, three misses, when no miss is called, and the free ball

The rules (WPBSA, simplified):

  • Foul: the white hits a ball not on first, or nothing. Your opponent gets 4 points, or the value of the ball you hit if that is higher. Hitting the blue first here costs 5.
  • Foul and a miss: if the referee judges you did not try your best, your opponent may have the balls put back and make you play again.
  • Three misses: when a straight line to a full-ball hit on a ball on was open, a miss is always called. After the second the referee warns you; a third loses the frame.
  • No miss when hitting the ball on is impossible, if you play at it hard enough to reach it.
  • Free ball: if your opponent's foul leaves you snookered, you may name any ball as the ball on for that shot.

So in a real snooker, an honest attempt with enough pace matters as much as the aim.

Chapter 2 — One cushion

4 · Aim at the mirror ball

Top view of the white near the baulk line, the blue in the middle, the red behind it; a cross on the direct line. A dashed line goes from the white down to a yellow point on the bottom side cushion and on to a dashed "mirror red" below the table. The white's track goes from the cushion point up to the red

  1. Picture the red reflected behind the cushion you will use (the mirror red).
  2. Aim the white's centre at the mirror red's centre.
  3. The yellow point where that line meets the cushion is your target. Look at it, not at the red.

Trick: reflect from where the white's centre touches the cushion, half a ball out from the rubber (post 07). Pick a mark on the rail level with your cushion point.

5 · Two routes, two windows

Two top views of the whole table. A yellow wedge from the white shows all the aims that hit the red first. 1: off the top side cushion, a long way to the cushion; the wedge is narrow, 48 mm at the cushion. 2: off the bottom side cushion, closer; the wedge is wider, 72 mm

Any contact on the red escapes, so each route has a window: all the aims that touch the red first.

Route (power 4) White to the cushion Room at the cushion Mirror aim as it is
1 · top side cushion 1.4 m about 5 cm misses ✗
2 · bottom side cushion 1.0 m about 7 cm hits ✓, right in the middle

Take route 2: more room, and the plain mirror works.

Watch out: check the whole path for other balls first. A route that clips a third ball is no route.

6 · Pace moves the aim

Three top views of the escape off the bottom side cushion. 1: power 3 aimed at the mirror red: the white comes off flatter and misses the red, cross. 2: power 3 with the cushion point 13 cm shorter: the white hits the red, tick. 3: power 4 aimed at the mirror red: it hits the red, tick

The mirror works when the white is still sliding at the cushion. At power 3 it is already rolling, so it comes off flatter (post 07). Route 2 (model):

Aim Room at the cushion Result
1 power 3, mirror misses ✗
2 power 3, cushion point 13 cm shorter about 4 cm ✓
3 power 4, mirror about 7 cm ✓

Two good ways: firmer and trust the mirror, or softer and aim shorter. Firmer has more room.

7 · Watch it: the escape

Clip: from the baulk end, a yellow dot marks the cushion point and a dashed line runs to it. The white is played at power 4 off the bottom side cushion, comes up past the blue and hits the red

Power 4, centre ball, aimed at the mirror red ✓.

8 · Where do the balls end?

Two top views of the whole table after the escape off the bottom cushion, each hitting the red in the middle of its window. 1: power 3: the red runs up to the top right, 24 cm from the corner pocket, and the white stops in the middle of the table. 2: power 4: the white travels round the top right of the table and stops 15 cm off the top cushion; the red stops 93 cm from the nearest pocket

Both escapes hit the red. What they leave is very different (model):

The red ends The white ends
1 · power 3 24 cm from the top-right pocket in the open, mid-table
2 · power 4 93 cm from any pocket 15 cm off the top cushion

The soft one gives your opponent an easy red. Here the firmer route is better twice: more room and a safer leave. Before you play, picture both balls after the contact.

Chapter 3 — Round the angles

9 · Nothing simple is on

Three top views of the whole table. The white is in baulk, the red near the top right corner. 1: the direct line hits the blue, cross. 2: off the top side cushion, the white hits the pink, cross. 3: off the bottom side cushion, it hits the black, cross

Check in this order: direct, one cushion each side, then two or more. Here the blue blocks the direct line, the pink blocks the top side cushion route, and the black blocks the bottom side cushion route.

10 · The double mirror

Diagram: the table seen from above, with a mirror copy of the table below the bottom cushion and a corner copy beyond the end cushion. The red is mirrored in the end cushion (point 1), then point 1 is mirrored in the bottom cushion (point 2), down and to the right of the table. A straight dashed line from the white to point 2 crosses the bottom cushion; folded at each cushion it becomes the real yellow path: white to the bottom cushion, to the end cushion, to the red

  1. Mirror the red in the last cushion the white will touch: point 1.
  2. Mirror point 1 in the first cushion: point 2.
  3. Aim at point 2. Where the line meets the first cushion is your target.

For two cushions that meet at a corner, point 2 is the red reflected through the corner.

Clip from the baulk end: two yellow dots mark the cushion points on the bottom side cushion and the end cushion. The white is played at power 4, goes down to the bottom cushion, up to the end cushion and back out to hit the red

Watch out: a rolling white comes off each cushion a little flatter, and two cushions add up. Here the first cushion point needed to be about 5 cm shorter than the double-mirror line (a turn of about 1.7°).

11 · More than one way out

Three top views, each a different escape that hits the red, with the room for error: 1: off the top side cushion, then the end cushion, 1.3 degrees. 2: off the bottom side cushion, then the end cushion, 1.1 degrees. 3: off the bottom side, then the top side, then the end cushion, 1.1 degrees

Route Cushions Room (power 4)
1 top side → end 1.3°
2 bottom side → end 1.1°
3 bottom side → top side → end 1.1°

On an open table, the one-cushion route off the top side cushion had 2.7°. Escapes round the angles have about half the room, which is why you check the simple lines first.

Chapter 4 — Swerve

12 · Curve round the ball

Two top views of the white, the blue in the middle and a red behind it, all on one line. Both shots aim to the left of the blue with right-hand side, power 3. Cue level: the white goes straight and misses everything, cross. Cue raised 20 degrees: the white starts left, passes the blue and curves right into the red, tick

When the cushions are shut, side with a raised cue curves the white (post 05):

  1. Aim past the blocking ball, on the side away from the curve (here left).
  2. Side towards the red (here right-hand side, half-way out).
  3. Raise the butt about 20°, power 3.

Side view of the swerve shot. The white with the blue ahead of it. The cue comes down at the white from above; a yellow wedge between the cloth and the cue shows 20 degrees. A small face shows the tip spot right of centre, and the power bars show 3 of 5

That is what "raised 20°" means at the table: the back of the cue lifted, so the cue comes down at the white (post 01).

Clip from behind the white with the cue raised and the tip on the right of the white. The white starts to the left of the blue, curves back to the right after passing it, and hits the red
Cue The same aim and side
level goes straight, misses the red ✗
raised 20° curves round the blue into the red ✓

The room is small: only about 1° of aims made it round (model). Prefer a cushion when one is open.

13 · Choosing the way out

Ask Why
Is a direct edge free? then you are not snookered at all
Which one-cushion route has the most room? the plain mirror at power 4 is the easiest shot
Is any third ball on the path? a clipped ball is a foul
Where will the red and the white end? a safe leave is worth a little room
Cushions all shut? two cushions (half the room), then swerve
Is there a full-ball line open? then a miss is always called: take the escape you hit most often

Try it at the table

Drill Set-up Look for
Edges the white, a colour and a red in a line; move the colour sideways when both edges are clear
Mirror ball the white in the D, a red near the pink spot, a colour in between find the cushion point before you get down
Window the same, aim 2 cm left and right of your point which aims still hit
Two paces the same route at power 3 and power 4 how much shorter the soft one needs
Leave the same escape; mark where the red and the white stop which pace leaves the red far from pockets
Corner a red near a corner, the white in baulk reflect through the corner; hit the red
Swerve a ball 60 cm in front of the white, a red 80 cm behind it curve round with the butt raised

Cheat-sheet
Snookered no ball on with both edges clear
Foul 4 points, or the value of the ball hit if higher
Miss not your best try: balls back, play again; a full-ball line open: three misses lose the frame
Free ball snookered after a foul: name any ball as the ball on
One cushion the white's centre at the mirror ball
Choose most room, no third ball, safe leave
Power 4 the mirror works as it is; softer: aim shorter
Two cushions mirror in the last cushion, then the first; hit a little shorter
Swerve aim past, side towards the ball on, butt raised about 20°

What's next

10 · Multi-ball shots. Plants, sets, cannons and kisses: using one ball to move another.

References

  • WPBSA, Official Rules of the Games of Snooker and English Billiards (2024-25): Section 2 Rule 17 (snookered), Section 3 Rules 11 (penalty values), 12 (free ball) and 14 (foul and a miss). https://www.wpbsa.com/rules/
  • Dr. Dave Alciatore, kick-shot (escape) aiming with the mirror (ghost table) method; swerve and cue elevation. https://billiards.colostate.edu/
  • Windows, pace corrections, where the balls stop and the swerve come from the physics model. They change with the table, the cloth and your pace; the drills show your own.

Note: this post is in progress. Planned additions: an escape off the baulk cushion, and escapes using side off the cushion.