🎯 Free tool
Pool Cut-Angle Trainer
Put the cue ball, the object ball and the target pocket where they are on your table. The cut angle, the aim fraction you should see from behind the cue ball, and the margin for error all come out of the layout.
three-quarter ball · 76% ball overlap
The pocket accepts ±2.48° of object-ball error from here — about ±2.5 mm of slack at the contact point.
Place the contact point yourself
Tap the cloth where the centre of the cue ball has to be at the moment it touches the object ball. Then the shot is played from your placement, not from the right answer.
Nothing is drawn until you commit: no aim line, no ghost ball, no head-on view. Place it by eye, the way you have to when you are down on the shot, and the simulation plays the line you actually chose.
Pick one of the named shots above to land on a layout worth studying, or drag the cue ball or the object ball anywhere on the cloth and tap a pocket to aim at it. The cut angle is measured from the layout, not set by you. Yellow is the object-ball path, purple is the cue-ball path into the ghost-ball position, and the faint dotted line is where a stun shot sends the cue ball afterwards. “Play the shot” hands the layout to the same simulation the pool games run, so what you watch is what that shot does.
The lines are ideal geometry: a stun shot with no side spin and no cut-induced throw. Playing the shot is not — it runs the simulation behind 8-ball and 9-ball here, with cloth drag, cushions and real pocket mouths, so the ball can rattle out even when the aim was right. A real table adds throw on angled hits on top of both.
The five aim pictures
The whole method fits on one sheet. Each row is what the two balls look like from behind the cue ball, the cut angle that produces it, and the shot seen from above. Print it and keep it in the cue case — the picture is what you use at the table, not the number.
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full ball 0° cut 100% ball overlap
From behind the cue ball From above -
three-quarter ball 14° cut 76% ball overlap
From behind the cue ball From above -
half ball 30° cut 50% ball overlap
From behind the cue ball From above -
quarter ball 49° cut 25% ball overlap
From behind the cue ball From above -
thin cut 70° cut 6% ball overlap
From behind the cue ball From above
Dashed line: where the cue ball must arrive — its centre one full ball behind the object ball, on the line to the pocket. Dotted line: a stun shot sends the cue ball away at ninety degrees to the object ball, whatever the cut angle is.
Pool Cut-Angle Trainer · juju.games
How to use it
- Start from a named shot — straight in, half-ball, thin cut, into the side, full length, or cue ball on the rail — or drag the two balls to where they sit on your table and tap the pocket you are shooting at.
- Read the cut angle and the aim fraction. The outlined ghost ball is where the cue-ball center must arrive; the head-on view is what that looks like from behind the cue ball.
- Check the margin line. The same shot allows far less error from six feet than from two, which is the real reason long cuts miss.
- Press “Play the shot” to watch the object ball take the contact line while the cue ball leaves along the tangent at ninety degrees to it.
What the diagram teaches
An aiming line to the pocket only tells you where the object ball should travel. The missing step is the contact point: at impact, the cue-ball center must sit one full ball diameter behind the object ball on that line. The outlined ghost ball makes that invisible position visible, and the head-on view turns it into the overlap you can actually see when you are down on the shot.
The margin line is the part most aiming diagrams leave out. A pocket accepts a fixed width, so the angular error it forgives shrinks as the object ball gets further away — the same aim that pots from a foot away misses from six. That is an argument for position play, not for aiming harder.
The lines assume a stun shot between equal balls with no side spin and no cut-induced throw, which isolates the geometry. Playing the shot does not assume it away: the layout is handed to the same simulation the pool games on this site run, so the ball can catch a pocket jaw and stay up. What neither models is cut-induced throw, which on a real table runs an angled shot a couple of degrees thin of the ghost-ball line.
Frequently asked questions
What is the ghost-ball aiming method?
Imagine a second cue ball touching the object ball on the side opposite the pocket. Aim the real cue-ball center at that imagined center. The two ball centers then line up with the pocket at impact.
Why is a half-ball hit about a 30-degree cut?
The fraction of the object ball you cover is one minus the sine of the cut angle. At 30 degrees the sine is a half, so you cover half the ball and the cue-ball center lines up with the object ball’s edge. A quarter-ball hit is about 49 degrees.
How much can I miss by and still pot the ball?
It depends almost entirely on distance. The tool reads out the angular error the pocket still accepts for the current layout and converts it to millimetres of slack at the contact point, which on a long shot is often only one or two.
Does it include spin and throw?
The aiming lines assume a stun shot with no side spin, so the cue ball leaves at ninety degrees to the object ball. Pressing play runs the shot through the same engine as the pool games, which adds cloth drag, cushion rebound and pocket mouths. Cut-induced throw is not modelled anywhere, so on a real table expect an angled shot to run a couple of degrees thin of the ghost-ball line.
Can I put this trainer on my own website?
Yes. Copy the responsive iframe from the embed section; it carries the layout that is on screen. The brand credit is visible and optional; do not hide it or replace it with keyword-heavy link text.
Does it work on a phone?
Yes. Drag the balls with a finger and tap a pocket to change the target. The canvas redraws at the screen’s pixel density so the lines and balls stay sharp.
Ready to judge the angle inside a rack? Play 8 Ball Pool against the computer.
Want the rule context too? Read 8-Ball vs 9-Ball Rules.