Rails, cushions and diamonds
The rails are the raised wooden frame around the playing surface, and the rubber cushions on their inside edge are what the balls bounce off. (Players often say "rail" for the cushion too.) The short rail at the end you break from is the head rail; the one at the far end is the foot rail. WPA specifications allow rails 4 to 7.5 inches wide including the cushion.
The inlaid markers on top of the rails are the sights, usually called diamonds. A WPA table has 18 of them (or 17 plus a nameplate), spaced 12.5 inches apart on a 9-foot table and 11.5 inches on an 8-foot table. They mark eighths of the playing surface's length and quarters of its width, measured between cushion noses, which is why the bank and kick systems count in diamonds.
The strings, the spots and the kitchen
The WPA rulebook divides the table with imaginary lines called strings:
- Long string: the line down the center of the table, from rail to rail lengthwise.
- Head string: the line marking off the quarter of the table nearest the head rail. Because the diamonds mark eighths of the length, that is level with the second diamond from the head rail.
- Foot string: the matching line for the quarter of the table nearest the foot rail.
- Center string: the line between the two side pockets.
- Spots: the head spot is where the head string crosses the long string; the foot spot is where the foot string crosses it; the center spot is where the center string crosses it. The front ball of the rack sits on the foot spot.
- The kitchen: the area between the head string and the head rail. Under WPA rules, most breaks, and ball in hand after some fouls, start from here.
When a ball has to be re-spotted, WPA rules place it on the long string as close to the foot spot as possible, between the foot spot and the foot rail.
Pockets
A pool table has six pockets: four corners and two sides. WPA specifications set the corner pocket mouth at 4.5 to 4.625 inches and the side mouth at 5 to 5.125 inches, traditionally half an inch wider than the corners. Wikipedia describes WPA pockets as 1.75 to 2.25 times the ball's diameter, and British-style pockets as 1.6 times.
Drop pockets catch each ball in a basket under the pocket (WPA baskets must hold at least six). Ball-return tables send pocketed balls through internal channels to one collection box, which is common on commercial tables. See pool tables for more.
Table sizes
A table's nominal size, such as "9 foot," describes the table, not the playing surface inside the cushions, and every regulation size keeps a 2 to 1 length-to-width ratio.
| Table | Playing surface | Source |
|---|---|---|
| 9 ft (tournament) | 100 x 50 in | WPA |
| 8 ft (WPA spec; Dr. Dave calls it "pro 8") | 92 x 46 in | WPA |
| 8 ft (typical home) | 88 x 44 in | Dr. Dave Alciatore and most manufacturers |
| 7 ft "bar box" | about 70 to 82 x 35 to 41 in | Dr. Dave Alciatore; varies by maker |
Bar-box tables vary enough that you should check a specific table's measurements; the equipment section covers the manufacturer differences. The WPA puts the bed height, floor to playing surface, at 29.25 to 31 inches.
The balls
WPA pool balls are 2.25 inches in diameter (within 0.005 inch) and weigh 5.5 to 6 ounces. Balls 1 to 7 are solids, 9 to 15 are stripes, and the 8 belongs to neither group.