The Raw Math Behind Craps Buy Bet Vig
You walk up to a $10 minimum table, drop $20 on the layout, and tell the dealer you want the 4 for $20. He nods, slides you $39 in chips, and quietly pockets a $1 commission. That single dollar is the entire game. The Craps Buy Bet Vig Rules dictate that you pay a 5% commission on your wager to get true odds on the 4, 5, 6, 8, 9, and 10. On a $20 buy, the vig is $1. On a $100 buy, it is $5. On a $25 buy, most joints still charge $1, and that is where the edge evaporates. π²
Why the 5% Commission Changes Everything
Place bets on the 4 or 10 pay 9:5. Buy bets on the same numbers pay 2:1. The difference looks massive until you factor in the commission. A $20 place bet on the 4 wins $36. A $20 buy bet on the 4 wins $40 minus the $1 vig, netting $39. That is a $3 swing per hit, which sounds like free money. But the house edge on a $20 buy bet at 5% vig is 4.76% β identical to the place bet. The commission is not a fee on your winnings; it is a tax on your handle, collected whether you win or lose. That is the brutal truth most players never internalize.
The $25 and $39 Thresholds That Break the Vig
Here is where Craps Commission Bet Strategy separates the sharp from the sucker. On a $25 buy bet, the vig should be $1.25, but virtually no casino charges quarters. They round down to $1, which drops the house edge to 3.85% β better than the place bet. On a $39 buy, the vig is $1.95, rounded to $1, and the edge collapses to roughly 2.5%. That is a massive shift. The optimal buy bet on the 4 or 10 is $39, not $20, not $25. You are exploiting the rounding convention, not beating the math. π―
When the Dealer Charges Vig Upfront vs. On the Win
Some houses collect the commission only when the bet wins. Others collect it the moment you make the wager. This is not a cosmetic difference. If the vig is collected upfront, you lose that dollar even on a seven-out, which inflates the effective house edge by 0.5% to 1.2% depending on your bet size. If the vig is collected on the win, your expected loss drops because the commission is only paid on resolved winning bets. Always ask the dealer: "Is the vig on the win or on the drop?" The answer determines whether you are playing a 2.5% game or a 4.5% game. That is not a rounding error. That is your entire margin.
The 6 and 8 Buy Bet Trap
Buying the 6 or 8 is almost always idiotic. The place bet pays 7:6, and the true odds are 6:5. The gap is tiny. When you add a 5% commission on a $20 buy, the house edge jumps to 4.76% compared to 1.52% for the place bet. You are paying a premium for a payout that barely improves. The only exception is a $39 buy on the 6 or 8 with a $1 vig, which brings the edge down to roughly 2.1%. But even then, the place bet at $6 increments is cleaner and cheaper. Do not buy the 6 or 8 unless you are forced into a $39 unit and the dealer confirms vig-on-win.
The $50 Buy Bet Illusion
A $50 buy on the 4 or 10 pays $100 minus $2.50 vig, rounded to $2 or $3 depending on the house. If the vig is $2, your net is $98 on a $50 wager, which is a 2% edge. If the vig is $3, your net is $97, and the edge balloons to 4%. That $1 difference is the entire game. The Craps Buy Bet Vig Rules are not uniform across casinos, and any player who assumes otherwise is donating money. You must verify the rounding policy at every table, every shift, every property. The pit boss will not tell you. The dealer might not even know. You have to read the layout and watch the drop.
The Only Buy Bets Worth Making
On the 4 or 10, buy $39 and pay $1 vig on the win. On the 5 or 9, buy $38 and pay $1 vig on the win, which pays $57 minus $1 for a net of $56 β a 1.9% edge. On the 6 or 8, never buy unless the table forces $39 units and the vig is on the win. Everything else is a place bet or a pass line bet with odds. The commission is not negotiable. The rounding is. Exploit the rounding or go home. π°