House Edge Explained: What It Is, House Edge by Game, and the Bookmaker Margin

The house edge is the share of every bet that a casino expects to keep over the long run. It is built into the rules and the payouts of each game, so it is a fixed property of the bet, not something that changes with luck or with the time of day. In Vietnam it is called lợi thế nhà cái. This guide explains what the house edge means in practice, how it relates to RTP, gives the exact figure for the most common casino bets, and shows how the same idea works in sports betting as the bookmaker’s margin, also known as the vig or overround.

What the house edge means

A house edge of 2.7% means that, on average, the casino keeps about 2.70 of every 100 staked on that bet over a very large number of rounds. It says nothing about the next round: you can win or lose any single bet. What it does tell you is the expected cost of playing, which you can estimate before you start:

Expected loss = total amount staked × house edge

Total staked is every bet added up, not your deposit. If you play 200 rounds at 50 a round, you stake 10,000. At a 0.51% edge that is an expected cost of about 51; at 2.70% it is 270; at 14.36% it is 1,436. Same time at the table, very different price.

House edge and RTP

RTP (return to player) is the same number seen from the other side: RTP + house edge = 100%. A slot with an RTP of 96% has a house edge of 4%, and Spribe’s Aviator, published at 97% RTP, has a 3% edge. RTP is the figure slot studios publish (alongside volatility); the house edge is the figure table games are usually described with.

Which casino games have the best odds? House edge by game

The best odds in a casino are on the bets with the lowest house edge: blackjack played with basic strategy (about 0.5%), the Banker and Player bets in baccarat (1.06% and 1.24%), and any bet on single-zero roulette (2.70%). Among machine games, a full-pay 9/6 Jacks or Better video poker game returns 99.54% with perfect play. At the other end of the table, the baccarat Tie bet costs 14.36%.

These are the standard figures for the most common bets. Table rules change some of them, so they are for the usual version of each game:

Two things stand out. First, the edge depends on the bet, not just the game: in baccarat the Tie costs more than ten times as much as the Banker bet, and on an American wheel the five-number bet costs more than every other bet on the same table. Second, small rule changes matter. A blackjack table that pays 6:5 instead of 3:2 for a blackjack adds about 1.35% to the edge, taking it from about 0.5% to almost 1.9%.

For keno, the edge is set entirely by the paytable, which is why it varies more than any other casino game; the keno guide shows how to work it out from any paytable.

Where the edge comes from

Every bet pays a little less than its true odds. A straight-up number in European roulette wins 1 time in 37 but pays 35 to 1, as if there were only 36 numbers. In sic bo, Big and Small pay even money but both lose on a triple. In baccarat, the Banker hand wins more often than Player, so the casino takes a 5% commission on Banker wins. In bầu cua, an animal that shows on two or three dice pays 2:1 or 3:1, which looks generous but still works out at 7.87% in the house’s favour once all 216 outcomes are counted.

Why the house always comes out ahead

The law of large numbers. In a short session, results swing widely — that is variance, and it is why players can and do finish a session ahead. Over many thousands of rounds, though, the actual result settles closer and closer to the house edge. The casino does not need to win any particular round; it needs volume, and it gets it from all of its players together.

Betting systems do not change this. Doubling after a loss, following “hot” numbers or switching tables rearranges when you win and lose, but every unit you stake still carries the same edge, so the expected cost is unchanged. The only thing that lowers it is choosing bets with a lower edge, or staking less in total.

The bookmaker’s margin: vig and overround

Sportsbooks build the same thing into their odds. Turn each price into an implied probability (1 ÷ decimal odds) and add them up: a fair book would total exactly 100%. The amount over 100% is the overround, and the share the bookmaker expects to keep — the vig, juice or hold — is 1 − 1 ÷ overround.

To see what the odds would be without the margin, multiply each price by the overround: 1.90 × 1.0526 = 2.00, a true coin flip. The lower the overround, the less the book keeps on that market, so comparing it across bookmakers is a quick way to compare prices. Two-way markets such as Asian handicap and over/under totals are usually priced tighter than three-way 1X2 markets, and the same margin is built into every cash-out offer.

Where to compare games and odds

22bet and 20Bet both run live baccarat, blackjack and roulette tables alongside full sportsbooks, so you can check the version of each game — single or double zero, deck count, blackjack payout — before you sit down. For sports, see Vietnam betting sites for markets and welcome offers side by side.

Play responsibly

Knowing the house edge does not let you beat it; it tells you what playing costs. Treat every stake as money spent on entertainment, set a time and money limit before you start, never chase losses, and stop when it stops being fun. For adults 18 and over only.