Explainer · 7 min read
House edge: what lottery, casino and sports betting cost you
Every game of chance has a price, even if it isn't printed on the ticket. That price is the house edge: the share of every stake that, on average, stays with the operator. This guide puts the lottery, roulette, slot machines and sports bets side by side, with sources, and explains what the numbers mean for you. It compares costs, not chances of winning.
Updated 22 October 2026
Contents
What house edge and expected value mean
Expected value is what a bet or game returns on average over a very large number of repeats: each possible payout times its probability, added up, minus the stake. If it is negative, that is how much you lose on average per stake. The house edge is that average loss as a percentage of the stake.
A single-zero roulette wheel has 37 pockets, 18 of them red. If you win, you get €20 back (your stake plus €10).
Expected value = 18 ÷ 37 × €20 − €10 = €9.73 − €10 = −€0.27, or −2.7% of the stake.
Any single spin can win or lose. Over thousands of spins the result drifts towards the expected value. The idea is explained in more depth in expected value in betting.
House edge at a glance
| Game | Average payout | House edge | Where the figure comes from |
|---|---|---|---|
| Lotto 6 aus 45 (Austria) | 48.8% | 51.2% | Official game conditions: prize pool = 48.8% of the €1.50 price per line |
| Slot machine in an Austrian arcade (state licence) | 85 to 95% | 5 to 15% | § 5 Gambling Act (GSpG): payout ratio 85 to 95% |
| Single slot machine (state licence) | 82 to 92% | 8 to 18% | § 5 GSpG: payout ratio 82 to 92% |
| Single-zero roulette | 97.3% | 2.7% | Calculation: 1 ÷ 37 |
| Sports bet, main market of a top league | about 94 to 97% | about 3 to 6% | Bookmaker margin, typical range; side markets, live and outright bets usually higher |
| Sports bet with the Austrian betting fee passed on | about 89 to 92% | about 8 to 11% | Margin × 0.95 (5% Wettgebühr) |
As of October 2026. Lotto per the Österreichische Lotterien game conditions valid from 4 January 2026; slot machines per § 5 GSpG; sports betting margins are rough typical values, not official statistics.
These are averages over a very large number of games. In the lottery, a single draw can pay out more or less because of jackpots; slot machines vary by game within the legal range. The table compares what each game costs on average. It says nothing about the chance of winning any single game, and it isn't a recommendation to play any of them.
Lottery: about half goes to the prize pool
A line in Austria's Lotto 6 aus 45 costs €1.50. Under the game conditions 48.8% of that goes into the prize pool: 1.50 × 0.488 = €0.73 per line. Across all players, about €0.77 per line doesn't come back. It pays for administration, retail and duties, among other things.
Someone who plays two draws a week with 10 lines each pays 52 × 2 × 10 × €1.50 = €1,560 a year and gets about €761 back on average. The chance of six correct numbers is 1 in 8,145,060 per line. The lottery is mostly an expensive ticket to the dream of a jackpot. That is a legitimate choice; it just helps to know the price.
Casino: roulette and slot machines
Single-zero roulette has a house edge of 2.7% on almost every bet, whether on red, a single number or a dozen. No betting system changes that, including doubling after a loss; the Martingale guide shows why.
Under § 5 of the Austrian Gambling Act, slot machines in state-licensed arcades must pay out between 85 and 95% over an endless series of games (single machines: 82 to 92%). That sounds like a small loss, but slots are fast. At €1 a spin and 600 spins an hour you turn over €600. At a 10% house edge that is €60 an hour on average, even though you never risked more than one euro at a time. Online casinos without an Austrian licence aren't bound by these rules.
Sports betting: the margin is in the odds
In sports betting the house edge is built into the odds. For an even tennis match a bookmaker might offer 1.90 on both players instead of the fair 2.00. Stake €100 on each and €190 comes back whatever happens: €10 out of €200, a 5% margin. How to work it out for any market is shown in bookmaker margin and overround.
Two points matter in Austria:
- Margins vary a lot. Main markets of big leagues are cheapest; side markets, live bets and accumulators cost much more. In an accumulator the margins of every leg multiply.
- The betting fee. Since 1 April 2025 bookmakers owe a 5% fee on stakes. If one passes it on to you, your effective odds fall to odds × 0.95, and a 5% margin becomes about 9.75% (1 − 0.95 × 0.95). See Austria betting tax.
Unlike the lottery or a slot machine, sports betting lets you compare prices: the same outcome has different odds at different bookmakers, and always taking the best price means paying less margin. That is the idea behind line shopping.
Sure bets: when no margin is paid
Sometimes the best odds from different bookmakers on all outcomes of an event are so high that the combined margin across them drops below zero. That is a sure bet: you bet each outcome at the bookmaker with the best price, and before costs the return is about the same whatever happens.
Bookmaker A: 2.05 on player 1. Bookmaker B: 2.05 on player 2. 1 ÷ 2.05 + 1 ÷ 2.05 = 0.976, or 97.6%.
€100 on each side: €205 back in either case, +€5 on €200 staked (2.5%), if both bets are accepted at those odds and stand.
That sounds better than it is in daily practice. The costs simply appear elsewhere: odds move between the two bets, bookmakers void bets or limit accounts, a passed-on betting fee can eat the margin, and software costs money. Real results vary and can be negative. Whether this counts as gambling at all is discussed in is arbitrage betting gambling?.
What this means for you
- Know the price. Whoever plays pays the house edge on average: about half the stake in the lottery, 2.7% in roulette, and anywhere from a few percent to much more in sports betting, depending on market and fees.
- Turnover counts. A small percentage of a large turnover is a lot of money. Think in euros per month, not percent per game.
- No system removes the house edge. In the lottery, roulette and slots you can't avoid it. In sports betting you can only reduce the margin by finding better prices, not with lucky charms or tips.
- Set limits. Decide on a budget you can afford to lose. If gambling is causing problems, our responsible gambling page lists free help.
If you want to see price differences between bookmakers for yourself, ArbVantage shows them for the bookmakers where you have accounts and works out the stakes. The 14-day trial shows everything paying users see.
Frequently asked questions
What is the house edge of the lottery?
In Austria's Lotto 6 aus 45, 48.8% of the €1.50 per line goes into the prize pool, according to the official game conditions. On average players get about 49 cents back per euro staked, so the house edge is about 51%.
What is the house edge in roulette?
With a single zero it is 2.7% on almost every bet, because 1 of the 37 pockets is green. No betting system changes this, including doubling after losses.
How big is the bookmaker margin on sports bets?
On main markets of top leagues it is typically about 3 to 6%; on side markets, live bets and outright bets usually more. If a bookmaker in Austria passes on the 5% betting fee, the effective cost rises further.
Do sure bets have no house edge?
When the best odds across bookmakers imply less than 100% in total, you pay no combined margin on that event. It isn't free of costs: odds move, bets get voided, accounts get limited and software costs money.
Sources
- Österreichische Lotterien: game conditions for Lotto 6 aus 45 and LottoPlus, valid from 4 January 2026 (points 7.1 and 10.1), published in the EVI (in German)
- Austrian Gambling Act (GSpG), § 5 state-licensed slot machines (paragraphs 4 and 5) (in German)
- RIS: Gebührengesetz 1957, § 33 TP 17 (betting fee) (in German)
- Unternehmensserviceportal (USP): Austrian betting fee (Wettgebühr) returns (in German)
- Levitt, S. D. (2004): Why are gambling markets organised so differently from financial markets? The Economic Journal 114(495), 223–246
As of October 2026, checked against the linked sources. A cost comparison, not a statement about chances of winning. Not betting advice.
Betting involves risk, even with sure bets: prices move, bets get voided and accounts get limited. Only use money you can do without. Our responsible gambling page lists free help.
Not betting advice. 18+. Betting involves risk. See our disclaimer.