House Edge Explained: The Number Every Casino Game Is Built On

The house edge is the slice of every bet a casino expects to keep over the long run. It is built into the payouts: when a game pays you less than the true odds of winning, the gap becomes the casino's profit. A 2.70% edge means that for every $100 you wager, you should expect to lose about $2.70 on average. Not every time, but with near certainty over thousands of bets.

What the house edge actually measures

The house edge is your expected loss expressed as a percentage of the amount you bet. It is a property of the bet, not of you, your mood, or the dealer.

Three things it is not:

• Not the share of bets you lose. A 2.70% edge does not mean you win 97.3% of the time. On an even-money European roulette bet you win 48.65% of the time.
• Not a percentage of your bankroll. It applies to every dollar wagered, including winnings you bet again.
• Not a forecast for tonight. In one session you can win or lose far more than the edge suggests. The edge describes the average across a very large number of bets.

Where the edge comes from: paying less than true odds

The cleanest example is a single-number bet on European roulette. The wheel has 37 pockets, so the true odds against your number are 36 to 1. The casino pays 35 to 1.

Picture betting $1 on every one of the 37 numbers in a single spin. You stake $37. One number wins and pays $35 plus your $1 back, so $36 comes home. You lost $1 out of $37 wagered: 1/37, or 2.70%.

The same 1/37 appears on every European bet, which is no coincidence. A split covers 2 numbers and pays 17 to 1: EV per $1 = (2/37 × $17) − (35/37 × $1) = ($34 − $35) ÷ 37 = −1/37. A dozen covers 12 numbers and pays 2 to 1: (12/37 × $2) − (25/37 × $1) = −1/37 again. Each payout is set as if the zero did not exist, and the zero is the casino's cut.

An American wheel adds a 00 pocket but keeps the same 35 to 1 payout. Cover all 38 numbers with $38, get $36 back, and you lose $2 of $38, or 5.26%. One extra pocket nearly doubles the price.

Other ways the edge gets built in

• Commission. In baccarat the Banker hand wins slightly more often than Player, so winning Banker bets pay 95 cents per dollar after a 5% commission. With Banker winning about 45.86% of hands, Player 44.62%, and ties (a push for these bets) 9.52%, a $100 Banker bet averages 0.4586 × $95 − 0.4462 × $100 ≈ −$1.05. With unrounded probabilities it comes to −$1.06, an edge of 1.06%.
• Rule asymmetry. In blackjack you act first. If you bust, you lose on the spot, even if the dealer would have busted too. Basic strategy, doubling, splitting and the 3:2 blackjack payout claw most of that back, leaving roughly 0.3% to 1% depending on the rules.
• Pay tables. Slots, video poker and keno simply pay out less in total than the probabilities justify. The edge is whatever the pay table leaves behind.

House edge by game

Edges vary by a factor of more than 50 across a casino floor. These figures assume correct play wherever strategy matters.

Notice that the Tie bet sits on the same baccarat table as the 1.06% Banker bet. The game you pick matters, but so does the bet you pick inside the game. The glossary defines terms like RTP, push and hold.

From percentages to dollars per hour

A percentage is abstract. Your expected cost per hour is not. Multiply four numbers:

Using commonly cited playing speeds:

• Blackjack: $10 × 70 hands × 0.5% = $3.50 per hour
• European roulette: $10 × 35 spins × 2.70% = $9.46 per hour
• American roulette: $10 × 35 spins × 5.26% = $18.42 per hour
• Baccarat Banker: $25 × 70 hands × 1.06% = $18.55 per hour
• A $1 slot at 92% RTP: $1 × 500 spins × 8% = $40.00 per hour

The slot line surprises people. A $1 bet feels small, but at several hundred spins an hour you wager $500, and 8% of $500 is $40. Speed matters as much as the edge.

Why you can lose far more than the house edge

The edge is charged on every bet, not once on the cash you brought. Winnings you bet again get charged again.

Say you bring $100 to an American roulette table and bet $10 a spin for three hours. At 35 spins an hour that is 105 spins and $1,050 in total wagers. Expected loss: $1,050 × 2/38 = $55.26, more than half your starting money, from a 5.26% edge.

Keep playing until the $100 is gone and you will lose all of it, eventually, with near certainty. This is why casinos track hold: the share of the money players buy in with that the casino ends up keeping. Hold usually runs well above the edge, because the same dollars cycle through many bets. The guide to how casinos make money covers hold and theoretical loss in detail.

Can the house edge ever be beaten?

Mostly no. Honestly, occasionally, a little.

• Betting systems: no. Doubling after losses, or any other pattern, changes how your results are spread out, not their average. Every bet keeps its edge. The Martingale math shows exactly why.
• Card counting: yes, in principle. Edward O. Thorp showed in Beat the Dealer (1962) that blackjack's edge shifts as cards leave the shoe. The resulting advantage is small, the swings are large, and casinos can shuffle early, cap bets, or ban counters. See card counting explained.
• Video poker: rarely. Full-pay Deuces Wild returns 100.76% with perfect strategy, but it is hard to find and unforgiving of mistakes. A common pay table like 8/5 Jacks or Better returns 97.30%, a 2.70% edge.
• Choosing better bets: always. You cannot erase the edge, but you can shrink it. Moving a $10 bet from Tie (14.36%) to Banker (1.06%) cuts its expected loss from $1.44 to $0.11.

The bottom line

The house edge is the price tag hidden inside every payout. It comes from paying less than true odds, charging commission, or tilting the rules, and it is charged on every dollar you wager, again and again.

You can lower it by choosing games and bets carefully, and you can control what it costs by controlling bet size and time. You cannot make it disappear with a system. If you gamble for entertainment, treat expected loss as the ticket price. If it stops feeling like entertainment, help is available.