One module, 36 outcomes
Two six-sided dice produce 36 equally likely combinations. A 7 can be made six ways, a 6 or 8 five ways, a 2 or 12 one way each. Every probability on the site starts from those counts.
House edges are then computed, never typed in. For each bet the module takes the payout, multiplies it by the chance of winning, subtracts the chance of losing, and reports the result as a share of the amount decided. The tables you see on bet pages, including the ones inside the house edge comparison, are rendered from that output.
| Bet | Pays | House edge | Per roll |
|---|---|---|---|
| Pass Line | 1 to 1 | 1.41% | 0.42% |
| Place 6 | 7 to 6 | 1.52% | 0.46% |
| Odds on 6 | 6 to 5 | 0.00% | 0.00% |
| Field | 1 to 1; 2 pays 2 to 1; 12 pays 2 to 1 | 5.56% | 5.56% |
| Any Seven | 4 to 1 | 16.67% | 16.67% |
The pass line, worked through
On the come-out roll a 7 or 11 wins (8 of 36 ways) and a 2, 3 or 12 loses (4 ways). Any other total sets a point, and the bet then wins only if that point repeats before a 7.
Add up every path and the pass line wins 244 of every 495 decisions and loses 251. The difference is 7 out of 495, which is a house edge of 1.414%. The full rules are on the pass line page.
A place bet on the 6
A place bet on the 6 pays 7 to 6. Once it is working, only a 6 or a 7 decides it: five ways to win, six ways to lose. Bet $6, and over 11 decisions you expect to win $7 five times ($35) and lose $6 six times ($36).
That leaves a $1 loss on $66 wagered, or 1.515%. The same method gives 4.000% on the 5 and 9 and 6.667% on the 4 and 10, which is why the place bets guide treats the 6 and 8 differently.
The odds bet: zero edge
After a point is set you can back the pass line with an odds bet. On a point of 6 it pays 6 to 5, and the 6 still has five ways to win against six ways to lose. Five wins of $6 is $30, six losses of $5 is $30. Nothing is left for the house.
Odds bets, and lay odds on the don’t side, are the only wagers in the casino with a house edge of exactly 0.000%, and the module shows that for every point. The odds bet guide explains how much you can add.
The field and a proposition bet
The field wins on 3, 4, 9, 10 and 11 at even money (14 ways) and on 2 and 12 at 2 to 1 (2 ways, paid double). It loses on 5, 6, 7 and 8, which is 20 ways. Per $1 on 36 rolls: plus $14, plus $4, minus $20, a loss of $2. That is 5.556%. When the 12 pays 3 to 1 instead, the module returns 2.778%.
Any Seven in the middle of the table pays 4 to 1 and wins 6 ways out of 36. Six wins of $4 bring in $24 and thirty losses cost $30, so $6 goes to the house on every $36 bet. The edge is 16.667%, the highest on the standard layout.
Seeded simulations and tests
The strategy lab and the race charts on strategy pages run simulated shooters. Every simulation uses a fixed seed, so the same settings give the same result every time you load the page, and anyone can reproduce a chart we publish.
The module also has tests. They compare its output with the figures published in standard references for craps: 1.414% on the pass line, 1.364% on don’t pass, 1.515% on the 6 and 8. If a code change moved any of those by a rounding step, the test fails and nothing ships until it passes.
One quick check you can do at a table: a $6 place bet on the 8 that pays $7 is correct. If the dealer pays $6, what edge are you playing against then?