By the BonusWithoutDeposit editorial team · Last updated October 2026 · How we review
One of the fundamental facts of gambling is that the casino, whether it is a building with chandeliers or a site on the internet, can expect to earn more than all of its players put together (we have never met an exception). The foundation of the whole "business", as we have often written, is mathematics, and in particular the calculation of probabilities: every game is built so that, over a long enough series of bets, a known share of the money staked stays with the house, and that share is called the "house edge".
The same fact, seen from your side as a player, is the "payout percentage" or "RTP" (return to player): the share of the money staked that the game returns on average. The two are the faces of one coin, so that a slot with an RTP of 96 per cent has a house edge of four per cent; this page explains where that edge comes from, how it behaves in the short and in the long run, and what it means game by game.
The casino wins in two ways, often at the same time, and we find it useful to separate them. The first is to offer games in which the probabilities favour the house, while the second, more subtle, is to pay the player's winnings at slightly less than the odds would require, and roulette shows it better than any definition. The European "wheel" has thirty-seven numbers (from 0 to 36), so that a bet on a single number has one chance in thirty-seven of winning and should, in fairness, pay thirty-six times the stake. The casino pays thirty-five, and the difference, one unit in thirty-seven, is a house edge of 2.7 per cent.
The American wheel adds a second zero (the "double zero"), and with thirty-eight numbers and the same payment the edge rises to 5.26 per cent, almost double. The rules look identical, the table looks the same, and yet for every hundred staked the American roulette keeps on average more than five, against less than three for the European one!
Almost every casino game has a negative "expected value" for the player (the average result per bet), which means that over a long series of bets he or she will lose, on average, the house edge multiplied by the amount staked. In the "short run", however, anything can happen, and a series of winning hands is entirely possible; the distance between what the mathematics predicts and what actually happens on a given evening is measured by the "standard deviation", which is large over a hundred bets and becomes small over a hundred thousand (relative to the amount staked).
This is the reason why the casino does not fear the "lucky" player of one evening, while the player should not trust the lucky evening. The edge works slowly, but it always works, and the only player it cannot reach, as we like to repeat, is the one who stops!
The edges vary considerably from one game to another, and the table below, which we compiled from the published rules, shows the typical values (for the slots they depend on the single title, and on the version that the casino has chosen):
| Game | Typical house edge | Typical RTP |
|---|---|---|
| Blackjack, with basic strategy | about 0.5 % | about 99.5 % |
| Video poker, Jacks or Better (full pay) | 0.46 % | 99.54 % |
| Baccarat, bet on the banker | 1.06 % | 98.94 % |
| European roulette | 2.70 % | 97.30 % |
| American roulette | 5.26 % | 94.74 % |
| Slots without jackpot | 2 to 6 % | 94 to 98 % |
| Progressive jackpot slots | up to 12 % or more | 88 % or less |
The figures for blackjack and for video poker assume that the player makes the right decisions, and this is the point where those games differ from all the others. Roulette has fixed probabilities, whatever the player does. In blackjack the edge depends on the choices made at the table (when to draw, when to stand, when to double), so that if you play by "instinct" you can give the house an edge several times larger than the half per cent of the table.
The edge, finally, is not the only thing that changes from one bet to another. A bet on "red" at roulette and a bet on a single number have the same edge of 2.7 per cent, but the first wins almost one time in two and pays the stake, while the second wins one time in thirty-seven and pays thirty-five times, and the smaller the risk, the smaller the reward, and the choice between the two is, in our view, a matter of temperament rather than of mathematics.
Besides the mathematics, a casino has an interest in keeping its customers at the tables for as long as possible (the longer, the better), since, as we have seen, the longer they play, the closer their results come to the edge. Anyone who has entered a real casino (in a city, in a resort, in a holiday town) will have noticed that it offers no points of reference (no clocks, no windows, "exits" that are not easy to see), and it is good practice to fix one's own landmarks on the way in, so as to find the way out when one has decided to leave.
The online casino cannot hold its players with "architecture", since one click is enough to leave it, and it uses the bonus instead. The "wagering" attached to a bonus obliges the player to place a volume of bets before withdrawing, which is the online equivalent of the corridors without clocks; our guide to casino bonuses and wagering requirements shows, with the figures, how to tell whether a bonus is worth more than it costs.
The share of the money staked that a game, or a casino as a whole, returns to the players on average. It is also called RTP, return to player.
They are two sides of the same figure: a game with an RTP of 96 per cent has a house edge of 4 per cent.
Blackjack and full-pay video poker, both around half a per cent, provided that the player makes the right decisions. Among the games of pure chance, baccarat on the banker and European roulette.
Because the double zero brings the numbers to thirty-eight while the payments stay the same, so the house edge rises from 2.7 to 5.26 per cent.
In the short run anything can happen, but over a long series of bets the edge prevails, and the only player it cannot reach is the one who stops.
The house edge is not a secret and not a trick: it is the price of the entertainment, written in the rules of every game, and in the regulated markets the RTP of each title must be published in its information panel (the small "i" on the screen). Knowing it allows the player to choose the games that cost less (European roulette rather than American, blackjack played with the right strategy, slots with a high RTP), and to remember that over the long run the mathematics always wins. 18+, and gambling should remain entertainment.