What is the house edge, and where does it come from?
The gap between two sets of odds
The house edge is not a fee, a rigged wheel, or a secret. It is the gap between the true odds of an outcome and the payout odds the game offers when you win. Because the gap is built into the game's published rules, you can compute it yourself with nothing but arithmetic.
A worked example: American roulette
A standard American roulette wheel has 38 pockets: the numbers 1 through 36, plus 0 and 00. Under the standard layout, a straight-up bet on a single number pays 35 to 1.
Run the arithmetic on a $1 straight-up bet:
- You win 1 time in 38, collecting $35 of profit.
- You lose 37 times in 38, losing $1 each time.
- Expected result per spin: (1/38 × $35) − (37/38 × $1) = ($35 − $37) ÷ 38 = −$2/38 ≈ −5.26 cents per dollar bet.
That 5.26 percent is the house edge on that bet. Notice what produced it: a fair payout on a 38-pocket wheel would be 37 to 1, and the game pays 35 to 1 instead. The two-unit shortfall, spread over 38 outcomes, is the whole trick.
The same arithmetic applies to the even-money bets. A bet on red covers 18 of the 38 pockets: (18/38 × $1) − (20/38 × $1) = −$2/38, the same ≈5.26 cents per dollar. Most standard bets on the American layout work out to this same figure — but not all of them. The five-number "basket" bet covering 0, 00, 1, 2, and 3 pays 6 to 1 under the standard layout, and the arithmetic there is (5/38 × $6) − (33/38 × $1) = −$3/38 ≈ −7.9 cents per dollar — noticeably worse than the rest of the board. The lesson generalizes: the edge belongs to the bet, not the game, and you have to run the numbers per bet.
What the edge does and doesn't mean
The edge is a long-run average, not a per-visit guarantee. Over a single evening anything can happen — that's the product. Over many thousands of wagers, results converge toward the average, which is why casinos treat the edge as revenue and why no betting pattern can change it: varying your bet sizes just re-weights wagers that each carry the same expected loss per dollar.
Games differ in how visible their edge is. Roulette's is fully computable from the layout, as above. Other games' returns depend on rules variations or on parameters chosen by the operator or manufacturer rather than on a single standard layout, so no honest general-purpose number can be quoted for them here — if you want the figure for a specific game in a specific jurisdiction, the regulator is the right place to look. In Nevada, casino games are overseen by the Gaming Control Board and Gaming Commission, which publish the state's gaming regulations.
Why this is worth knowing
Understanding the edge reframes gambling as what it is: paid entertainment with a computable price, not an income opportunity. The Responsible Gambling Council builds much of its safer-play education around exactly this idea. If the arithmetic above surprises you, that's the most useful surprise this site has to offer.