On the gaming floor · 8 min read

Where the house edge comes from

The advantage is built into the payout table, not into the shuffle. How it is calculated, and why it varies so widely between games.

The casino's advantage is not hidden in the shuffle, the wheel or the machine. It is written into the payout table, in plain sight, and it can be calculated from published rules. The house edge is simply the difference between the true odds of an outcome and the amount the house pays when that outcome occurs.

The clearest example: single-number roulette

On a European wheel there are 37 pockets, so the chance of hitting a chosen number is 1 in 37. A fair payout would therefore be 36 to 1. The casino pays 35 to 1. That one-unit shortfall, spread across 37 outcomes, is the entire advantage: 1 ÷ 37, or about 2.7 per cent of every amount staked.

Add a second zero, as American wheels do, and there are 38 pockets while the payout stays at 35 to 1. The edge rises to 2 ÷ 38, about 5.26 per cent — the same game, with the advantage roughly doubled. This is why the single-zero wheel standard in Europe and Asia matters more to a player's expected cost than any betting pattern.

Typical figures by game

Indicative house edge on common games
Game and bet	Approximate house edge	What drives it
Blackjack, liberal rules, correct play	0.3%–0.6%	Dealer rules on soft 17, doubling, splitting, blackjack payout
Baccarat, banker bet	about 1.06%	Fixed drawing rules plus the 5% commission on banker wins
Baccarat, player bet	about 1.24%	Fixed drawing rules
Baccarat, tie bet	4%–14%	Payout well below true odds; varies by paytable
Craps, pass line	about 1.41%	Payout of even money on an outcome slightly worse than even
Craps, any seven	about 16.7%	Short payout on a single-roll proposition
Roulette, single zero	about 2.70%	One untaken pocket
Roulette, double zero	about 5.26%	Two untaken pockets
Slot machines	2%–15%	Set in the paytable and the reel weighting; varies hugely by market
Keno	20%–30%	Very large gap between payout and probability

Why blackjack is the outlier

Blackjack is the only common table game where the player's decisions change the mathematics, which is why its edge is quoted against "correct play". The same table can run at well under one per cent for a player following basic strategy and at four or five per cent for one playing by instinct. Rule variations compound this:

Blackjack paying 6 to 5 instead of 3 to 2 adds roughly 1.4 percentage points to the edge — the single most damaging common rule change.
A dealer hitting soft 17 rather than standing adds around 0.2 points.
Doubling restricted to 9, 10 and 11 adds a small fraction of a point.
The option to surrender, and to double after a split, each give a fraction back to the player.

A table advertising "Blackjack pays 6:5" with a low minimum is almost always a worse proposition than a 3:2 table at twice the minimum.

Edge, hold and volatility

Three different numbers are often confused. The house edge is the expected cost per unit wagered. Hold is what the casino actually keeps from the money brought to the table, which is far higher than the edge because the same stake is wagered repeatedly as it circulates. Volatility describes how widely results scatter around the expectation, and it is the reason a high-edge game can still pay a large win and a low-edge game can lose steadily for hours.

Expected cost per hour is a more useful figure for a visitor than the percentage. Multiply the average stake by the number of decisions per hour by the edge: a £10 bet on a roulette table dealing 40 spins an hour at 2.7 per cent costs about £11 an hour in expectation; the same £10 on a craps proposition bet at 16.7 per cent costs nearly £70.

Slot machines are a different disclosure regime

Table edges can be derived from the rules. Machine returns cannot: the reel weightings sit in software, and a player cannot infer them from the display. Jurisdictions handle this in three ways — mandating a minimum return (Nevada requires at least 75 per cent, and actual averages run far higher), publishing aggregate return statistics by denomination, or requiring the return to be displayed on request. British machines and regulated online slots publish a return-to-player figure; most American floor machines do not.

What the edge does not mean

It is not a fee taken from each bet. It is a long-run average; any individual session can end anywhere.
It does not make a game "due" to pay. Independent trials have no memory, which is why progression systems cannot change expectation.
It is not the same as the chance of winning a session. A 2.7 per cent edge still leaves a near-coin-flip chance of being ahead after an hour.
It cannot be overcome by stake sizing. Changing the size of bets changes volatility, not expectation.

Questions

Which casino game has the lowest house edge?

Blackjack under liberal rules with correct play, typically under 0.6 per cent. Baccarat's banker bet at about 1.06 per cent is the lowest that requires no skill, and the odds bet behind a craps pass line carries no edge at all once the point is established.

Does the house edge mean I will lose 2.7 per cent of my money?

Of every amount staked, in expectation, over a long run. Because stakes recirculate, the proportion of the money you brought that you lose over a session is usually much larger or, with luck, negative.

Can card counting beat blackjack?

The mathematics is sound and has been published since the 1960s, but casinos respond with continuous shufflers, deeper penetration limits, flat-bet requirements and exclusion. It is not illegal in most jurisdictions, and casinos are generally entitled to refuse service.

Are slot machines in airports or supermarkets worse?

Usually, where published statistics exist. Returns tend to be lowest in locations with captive, low-frequency traffic and highest in competitive locals markets, which in Nevada means the suburban casinos rather than the Strip.

Last reviewed 1 January 1970. This page explains how something works; it is not legal advice and not a recommendation to gamble.