A lay bet is the mirror image of a buy bet: you bet that 7 will appear before a chosen box number. You are taking the more likely side of the race, so you risk more money than you can win. The casino earns its edge through the commission, and the timing of that commission can matter as much as the dice probability.
Read a lay wager as “seven before this number”
Lay bets are commonly offered against 4, 5, 6, 8, 9, and 10.
If you Lay 4, you want 7 before 4. If you Lay 9, you want 7 before 9. Other totals are neutral until one of the two relevant numbers appears.
| Number laid | Ways to roll laid number | Ways to roll 7 | Fair payout when 7 wins |
|---|---|---|---|
| 4 or 10 | 3 | 6 | 1:2 |
| 5 or 9 | 4 | 6 | 2:3 |
| 6 or 8 | 5 | 6 | 5:6 |
These are true-odds ratios before commission. Because your side is more likely, the payout is smaller than the amount at risk.
The simplest mental translation is: laying a number means betting against that number, with 7 as your winning event.
The vig is the price of standing on the favored side
Before commission, a true-odds lay race is mathematically fair. The casino adds a fee, usually called the vig or commission.
The Massachusetts Gaming Commission’s craps rules allow true-odds lay bets with a commission that may not exceed 5% under the cited rule and explicitly permit the licensee to collect the percentage only on winning wagers. The same rules list the true-odds payouts of 1:2 on 4/10, 2:3 on 5/9, and 5:6 on 6/8. See the Massachusetts craps rules for that regulatory example.
Other jurisdictions and casinos may handle the commission differently. Never assume “5% vig” tells the whole story. Ask whether the fee is based on the amount you can win, how it is rounded, and whether it is collected only on wins or up front.
Win-only commission produces three different edge levels
Using exact 5% commission on the amount won and collecting it only after a winning resolution, the common lay wagers have different percentages.
Lay 4 or 10
Risk $40 to win $20. A 5% commission on the $20 win is $1, so net profit is $19.
EV = (6/9 × $19) - (3/9 × $40)
EV = -$0.6667
House edge ≈ $0.6667 / $40 = 1.67%Lay 5 or 9
Risk $30 to win $20. Net profit after a $1 commission is $19.
EV = (6/10 × $19) - (4/10 × $30)
EV = -$0.60
House edge = $0.60 / $30 = 2.00%Lay 6 or 8
Risk $30 to win $25. With an exact $1.25 commission, net profit is $23.75.
EV = (6/11 × $23.75) - (5/11 × $30)
EV ≈ -$0.6818
House edge ≈ 2.27%Real tables may round commissions to convenient chip units, so actual effective percentages can differ from the exact mathematical examples.
Paying commission up front can make the same-looking bet materially worse
Suppose a player lays $40 against 4 to win $20 and pays $1 at booking. If 4 appears first, the player loses the $40 and has already paid the $1 fee. If 7 appears first, the player receives the $20 profit but the $1 fee was still paid.
That is worse than paying the vig only after a win because the fee is now charged on losing decisions too.
This is why two layouts can show the same “Lay 4” label while offering different value. The dice race and true-odds payout may be identical, but commission timing changes expected cost.
A player who compares only the ratio 1:2 is missing the part that creates the casino edge.
Lay bets are not the same as laying odds behind Don’t Pass
The language is similar, but the contracts are different.
A Lay 4 is a standalone number-versus-7 wager usually subject to a commission.
Laying odds behind Don’t Pass is a supplemental true-odds wager attached to an existing Don’t Pass contract after a point is established. True odds themselves do not carry a house edge when paid exactly.
Both can involve risking more to win less because the player is on the 7 side of a race. But one is a commission bet and the other is an odds extension of a line wager.
This distinction matters for accounting, placement, limits, and house edge. Do not use the phrases interchangeably.
A live-table example shows why amount selection matters
You want to Lay 10 and would like to win $25. Because 7 is twice as likely as 10 in the decisive race, you need to risk $50 before commission.
If the property charges 5% of the $25 win only after success, the commission is $1.25 before any house rounding rule. A 7 first produces $23.75 net profit. A 10 first loses the $50 risk.
If you instead hand the dealer an arbitrary $47 and say “Lay 10,” the crew may need to clarify what amount is intended, how the payoff rounds, and how the commission will be handled.
Clean units are not just etiquette. They prevent hidden rounding from changing the effective price of the wager.
Why frequent wins can make lay betting feel safer than it is
Lay wagers win more often than they lose because 7 is more common than any individual box number. That high hit rate can create a strong psychological impression of safety.
But probability of winning is only one part of risk. Stake size matters. On Lay 4, a common structure risks twice the amount that can be won before commission.
A player can therefore experience many small wins and then give back multiple wins when the laid number arrives. The commission steadily reduces the positive side of the distribution as well.
This is the same reason a high win percentage should never be confused with positive expected value.
Dealer placement and verbal confirmation are part of the wager
Lay bets are normally dealer-controlled. The player passes chips to the dealer, identifies the number to lay, and the crew places the chips in the correct location.
The dealer also needs to know the commission procedure and any house rounding convention. A supervisor may need to approve larger wagers or verify a nonstandard amount.
Late calls are especially risky. If the dice are already moving, a dispute can arise over whether the lay wager was accepted before the outcome became known. The safest practice is a clear call, clean amount, and visible dealer acknowledgement.
From a game-protection perspective, the mathematics and the booking process are inseparable.
Compare Lay 4 with Place-to-Lose 4 before assuming the names mean the same thing
Some rulesets distinguish a place-to-lose wager from a true-odds lay wager. The place-to-lose bet can use a fixed reduced payout without a separate commission, while a lay wager pays true odds and adds a vig.
The resulting house edges and chip procedures differ.
That is why a player should read the posted rules rather than using “bet against 4” as a generic category. The event can be identical—7 before 4—while the pricing mechanism changes.
This page focuses on the true-odds-plus-commission lay structure. For the broader family, compare buy bets, Don’t Pass strategy, and craps house edge.
A four-question check keeps lay-bet pricing honest
Before laying a number, answer these four questions:
- What amount am I risking and what amount am I trying to win?
- What true-odds ratio applies to this number?
- How is the commission calculated and rounded?
- Is the commission charged only when I win or whenever I book the wager?
If you know those answers, the lay bet is transparent. If you do not, the fact that 7 is the most common total is not enough information to price the wager.
Use the craps odds calculator and expected loss calculator if you want to compare stake structures over repeated decisions.