Casino games are games of chance with a built-in house edge. No rule set, strategy or timing turns that edge into an advantage for the player over time, and most players lose money over time. Nobody should gamble money they cannot afford to lose, and anyone struggling with gambling can contact a local support service. This article looks at how small differences in rules change what a game costs, and who decides which versions exist.
Same game, different rules
Two tables with the same name can be quite different products. A game is defined by its rules, and the house edge is a result of those rules together with the payouts. Change one detail and the long-run cost of playing changes with it, even if the game looks identical from the player’s side of the table.
The two sections below use simple examples to show this. Any figures here are illustrative arithmetic on textbook setups, not a description of any particular venue.
Roulette: one zero or two
A single-zero wheel has 37 pockets, and a double-zero wheel has 38. A straight-up bet on one number typically pays 35 to 1 on both. The true odds differ, though, because the extra pocket makes a win less likely without changing the payout.
For a hypothetical one-unit straight-up bet:
- Single zero: one win in 37 returns 35 units plus the stake, and 36 outcomes lose the unit. The expected result is (35 - 36) / 37 = -1/37, about -2.70%.
- Double zero: the same payout, but 38 pockets. The expected result is (35 - 37) / 38 = -2/38, about -5.26%.
The extra pocket roughly doubles the expected cost per unit wagered. The difference between the layouts is explored further in the discussion of the double zero.
Rules about what happens when the ball lands on zero can shift the cost again. Under the French rule known as la partage, an even-money bet loses only half its stake when zero comes up. On a single-zero wheel, that means the expected loss on such a bet is half of 1/37, which is 1/74 or about 1.35%, compared with about 2.70% without the rule. Whether a venue offers it depends on its jurisdiction and its own choices.
Blackjack: small rule changes, big arithmetic
Blackjack shows the effect of rules more than most games because there are many small variables. A few common examples:
- Blackjack payout. A natural blackjack paying 3 to 2 returns 15 units on a hypothetical 10-unit bet. Paying 6 to 5 returns 12 units, which is 3 units less each time it happens. Players who do not check the posted payout can sit down at a table that costs more.
- Number of decks. Games dealt from different numbers of decks have slightly different edges, a topic covered under number of decks and related rule variations.
- Dealer behavior on soft totals. Whether the dealer must stand or draw on certain hands changes the edge.
- Doubling and splitting restrictions. Limits on which hands you may double or how often you may split reduce the player’s options and so raise the cost.
- Surrender. Where offered, the option to give up half the bet on a bad hand modestly changes the edge.
The size of each effect depends on the full combination, which is why articles on blackjack mathematics and basic strategy specify the rules they assume. A strategy chart designed for one set of rules may be slightly wrong for another.
Other places rules hide
Rule differences are not limited to those two games:
- Ties. How tied hands are handled, discussed under push rules, can change a game’s cost.
- Payouts. In video poker, two machines with the same hands but different payouts for some combinations can return different amounts over time, which is why every line of the pay table matters.
- Extras. Optional extra wagers are rules too, and side bets tend to carry edges that differ from the main game.
- Betting limits. Table limits do not change the percentage edge, but they affect how much can be wagered and how quickly a bankroll can swing.
Who sets the rules
Rules come from several layers, and not every layer is a regulator.
Regulators and legislation may specify which games are permitted, set minimum standards for equipment or procedures, require rules to be posted, and in some places restrict certain variations. In some systems they also require approval before a game version is offered. They do this in the name of fairness and consistency rather than to guarantee a good deal for the player.
Operators typically choose from the permitted options. A venue may choose a table with more favorable or less favorable payouts for the same game, based on its business goals, its clientele and how much it wants to charge for the entertainment. This is one reason rule changes in the history of the industry, covered under rule changes over time, often track what the operator needs to maintain its margin.
Game designers and suppliers create the underlying versions. For electronic games, the math is fixed in the software, and the version has to pass testing before it is used.
The consequence is that legal does not mean equal. Many different rule sets can be lawful, and they are not equally costly.
How to compare versions sensibly
A few habits help when reading a rule sheet:
- Look for the payout on the main bet and any special hands, rather than only the name of the game.
- Check the rules that determine ties, surrenders and special cases.
- Treat every optional extra as a separate wager with its own cost.
- Remember that a lower house edge is still a house edge. A better rule set reduces the expected cost of playing; it does not create a profit.
The cost figures in published tables are long-run averages. A single session can end well above or below them, and short-term results say little about which rules are better.