What Is a Casino House Edge?
The house edge is the mathematical advantage built into every casino game, expressed as the percentage of each bet the casino expects to keep over the long run. It exists because winning bets pay slightly less than true odds. European roulette pays 35 to 1 on a 36 to 1 shot, creating a 2.7 percent edge. Blackjack with perfect basic strategy runs about 0.5 percent; keno can exceed 25 percent.
Where the edge comes from
No casino game cheats. The advantage is baked into the payout schedule. Roulette is the cleanest example: a European wheel has 37 pockets, so a single number wins 1 time in 37, yet the payout is 35 to 1 rather than the fair 36 to 1. Bet C$1 on every number for 37 spins and you will wager C$37 and get back C$36, guaranteed. That missing dollar, 2.7 percent of turnover, is the edge.
American wheels add a second zero, doubling the edge to 5.26 percent for the same payouts. The pattern repeats everywhere: blackjack pays 3 to 2 but the dealer resolves your bust before revealing their hand; the craps field bet pays even money on a proposition that hits 44.4 percent of the time; slots return a programmed percentage of everything wagered. The edge is not hidden, it is just rarely printed on the table.
What the edge costs you in dollars
Multiply your total wagers, not your buy-in, by the edge to estimate expected loss. Play 200 hands of C$10 blackjack with basic strategy and you wager C$2,000; at a 0.5 percent edge the expected cost is about C$10. The same C$2,000 cycled through a slot with 96 percent RTP (a 4 percent edge) carries an expected cost of C$80. Same money, sixteen times the price.
Short sessions swing wildly around those averages, which is the whole appeal, but the long run is unforgiving. This is also why betting systems fail: doubling after losses changes the size and timing of your bets, but every single bet still carries the same negative expectation. No sequence of house-edge bets adds up to a player edge.
House edge by game
Rough figures for common games: blackjack with basic strategy 0.5 percent (2 percent or worse if you play by feel), baccarat banker 1.06 percent, craps pass line 1.41 percent, European roulette 2.7 percent, American roulette 5.26 percent, online slots typically 3 to 8 percent, video poker from under 1 percent on good pay tables, and keno or lottery products 25 percent and up.
Two cautions. First, rule variations move the numbers: blackjack paying 6 to 5 instead of 3 to 2 adds about 1.4 percent to the edge, one of the worst trades in the casino. Second, side bets almost always carry edges of 5 to 15 percent regardless of the base game. If you want to pay less for your play, the main bets on the old games are consistently the cheapest seats in the house.
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