Set two numbers and read your aim. This free calculator applies the classic corner-5 formula — departure minus arrival equals first-cushion contact — and draws the three-cushion path on a live table diagram, so you can see why the number works, not just what it is.
Schematic diagram. Corner-5 numbers assume medium speed, a high-medium hit and one tip of running english; real tables drift slightly — see the notes below.
How the corner-5 numbers work
The corner-5 system overlays a fixed numeric grid on the table, and the calculator above uses the classic diamond-unit version of it:
- Departure (cue ball): the corner is 5. Going up the short rail from that corner, the diamonds are 6, 7, 8, 9. Going along the long rail away from the corner, values fall half a point per diamond: 4.5, 4, 3.5, 3… down to 1.5.
- Arrival (third cushion): counted on the opposite long rail from the far corner: the corner is 0 and each diamond adds one — 1, 2, 3, 4.
- First-cushion contact: the diamonds of the first long rail, counted 1–7 from the same side as arrival zero.
The whole system is one subtraction: departure − arrival = first-cushion contact. Cue ball at the corner (5), target the second arrival diamond (2): aim at first-cushion diamond 3. That is the around-the-table pattern professionals trust in deciding innings — and the one the diagram above draws for you. The site’s corner-5 article writes the same values ×10 (50 − 20 = 30); divide by ten and you are back to diamond units.
Using it at a real table
- Find your departure number. Stand behind the cue ball and project its position onto the numbering: near a corner it is ~5, on the short rail above the corner 6–9, along the long rail 4.5 and below. Between diamonds? Use halves — the slider moves in 0.5 steps for exactly that reason.
- Pick the arrival. Decide where on the third cushion the cue ball must land to meet the second object ball — that is your target number 0–4.
- Aim at the result. The calculator gives the first-cushion diamond. Aim through it at cushion height, play a high-medium hit with one tip of running english at medium speed, and let the geometry do the rest.
Important: aim numbers are cushion contact points, not ghost-ball targets, and the system assumes the standard stroke. If you load extra spin or fire harder, the rebound widens and the numbers drift — that is a stroke problem, not a system problem, as the aiming-systems overview explains.
Worked examples
| Cue ball (departure) | Target (arrival) | Aim (first cushion) | Pattern |
|---|---|---|---|
| 5 (corner) | 2 | 3 | The classic around-the-table reference shot |
| 6.5 (short rail) | 1.5 | 5 | Steeper entry, long natural line |
| 8 (high short rail) | 3 | 5 | Same aim, very different departure — feel the difference |
| 4 (long rail) | 1 | 3 | Shallow long-angle bank |
Recreate each of these on the diagram above, then on the 3ball simulator: place the balls, aim at the computed diamond and watch whether your stroke reproduces the system’s assumptions.
When the numbers drift
- Speed: harder strokes hold tighter lines and rebound longer; the system is calibrated for medium speed. Calibrate in “table lengths”, not muscle.
- Spin: corner-5 assumes one tip of running english. More spin lengthens the third-cushion arrival; reverse english shortens it dramatically — see the reverse-english guide.
- Cloth and humidity: new, fast cloth on a heated table plays “longer” than worn club cloth. Professionals re-test a reference shot before every tournament; do the same and shift your arrivals by the difference.
- Short-angle positions: when cue ball and target are close together on the same rail, the corner-5 range runs out (the calculator warns you). Switch to Plus 2 or a hold-up pattern instead.
Drill it free in the simulator
Numbers become instinct only through repetition. The free 3ball simulator overlays numbered diamonds on a physics-accurate table — set up any departure/arrival pair from this page, fire ten times at the computed diamond and watch the third-cushion arrival respond to your speed and spin. When a position looks unsolvable, the brute-force solver shows every three-cushion route through it. For the full theory, continue with the Diamond Systems Mastery guide or jump back to how to read the diamonds.