Two Numbers Every Player Should Know
Before you play any casino game — online or in person — there are two fundamental figures worth understanding: the house edge and the return-to-player (RTP) rate. They describe the same mathematical reality from opposite perspectives, and together they reveal how much of a long-term advantage the casino holds in any given game.
What Is the House Edge?
The house edge is the mathematical percentage of every bet that the casino expects to retain over a large number of wagers. It's built into every game by design.
For example, a house edge of 2% means that for every £100 wagered over time, the casino keeps an average of £2 and returns £98 to players. This doesn't mean you'll lose exactly £2 in any single session — variance means short-term results swing wildly. But over thousands of rounds, the math asserts itself.
What Is RTP?
Return-to-player (RTP) is simply the inverse of the house edge expressed as a percentage:
RTP = 100% − House Edge
A game with a 2% house edge has a 98% RTP. An online slot with a stated RTP of 96% has a house edge of 4%. The RTP tells you what proportion of all money wagered is paid back to players collectively over time.
House Edge Across Common Casino Games
| Game | Approximate House Edge | Notes |
|---|---|---|
| Blackjack (basic strategy) | 0.5% or less | Varies by rules and player skill |
| Baccarat (Banker bet) | ~1.06% | One of the best bets in the casino |
| European Roulette | ~2.7% | Single zero wheel |
| American Roulette | ~5.26% | Double zero significantly increases edge |
| Craps (Pass Line) | ~1.41% | Other bets can be much worse |
| Video Poker (optimal play) | 0.5%–2% | Depends on variant and strategy |
| Online Slots | 2%–15%+ | Varies widely; check the paytable or game info |
Why the House Edge Compounds Over Time
The house edge is applied to every single bet, not just your starting bankroll. This is why long sessions are statistically more costly — the edge compounds with each wager placed.
Consider this: if you play 500 rounds of roulette betting £5 per spin, your total amount wagered is £2,500. At a 2.7% house edge, the expected loss is around £67.50. This is regardless of wins or losses along the way — it's a mathematical expectation over time.
Volatility vs. House Edge
House edge is often confused with volatility (also called variance). They're different concepts:
- House edge tells you the long-term mathematical direction of your bankroll.
- Volatility describes how wildly results fluctuate around that average in the short term.
A low-volatility game might return small, frequent wins while steadily grinding down your bankroll. A high-volatility game might run cold for hours, then pay out a large win. Both can have the same house edge — but the experience is very different.
How to Use This Knowledge Practically
- Favour low-edge games: Blackjack, baccarat banker, and craps pass line offer among the best odds.
- Check RTP on slots: Reputable online casinos publish RTP figures in game info panels. Aim for 96% or higher.
- Beware of side bets: They almost always carry a much higher house edge than the main game.
- Set session budgets based on expected loss: Knowing the house edge lets you estimate realistic session costs.
The Bottom Line
No strategy eliminates the house edge — it's a built-in feature of every casino game. But understanding it empowers you to make informed choices: which games to play, which bets to avoid, and how long a bankroll is likely to last. Knowledge is your most reliable advantage.