Two numbers explain almost everything about casino results: the house edge (what a game costs on average) and variance (how far real results stray from that average).
RTP and house edge
RTP (return to player) is the percentage of all money wagered that a game pays back over a very large number of bets. House edge is the remainder. A slot with 96% RTP has a 4% house edge: for every 100 wagered, it keeps 4 on average.
The key word is wagered, not deposited. If you deposit 100 and keep re-betting your winnings until you have wagered 2,000, a 4% edge costs about 80 on average, not 4.
Typical numbers
| Game | RTP | House edge |
|---|---|---|
| Crypto casino dice/limbo originals | About 99% | About 1% |
| Blackjack, basic strategy | About 99% to 99.5% | About 0.5% to 1% |
| European roulette | 97.3% | 2.7% |
| Online slots | Usually 94% to 98% | 2% to 6% |
| American roulette | 94.74% | 5.26% |
Slots often come in several RTP versions and the casino chooses which one to run. The game's info or rules panel shows the version you are actually playing.
Variance: why short sessions feel random
The house edge is an average. Over a few hundred bets, luck easily outweighs it, in both directions. Lower win chances (higher multipliers, high-volatility slots) mean a wider spread: rare big wins, and long losing runs in between.
Example: 1,000 bets of 1 at a 1% edge and 49.5% win chance. The average result is -10, but most sessions land somewhere between about -72 and +52. Try your own numbers in the house edge & variance calculator.
Why systems do not work
- Martingale (double after a loss) wins small amounts often and loses everything occasionally. Ten losses in a row at 1 per base bet need 1,023 in losses before the eleventh bet.
- Reverse systems, patterns, "hot" numbers: each provably fair round is independent. Past results do not change the next one.
- No staking plan changes the average: total wagered × house edge.
Sizing a bankroll
- Decide the session budget first, as money you are prepared to lose in full.
- Smaller bets relative to the budget give longer sessions, but also more total wagered, so a higher expected cost.
- Rakeback and cashback return part of the edge; they reduce the cost but never make it negative on their own.
- Stop when the budget is gone. Do not top up to chase losses. See responsible gambling.
Clearing a bonus? The wagering calculator applies this maths to bonus terms.
Quick answers
What is the difference between RTP and house edge?
They are two sides of the same number. RTP is the share of wagers a game pays back over the long run; house edge is the rest. 97% RTP means a 3% house edge.
Does a higher RTP mean I will win more often?
Not necessarily. RTP is about the long-run average. How often you win depends on the hit rate and volatility of the game.
Can a betting strategy beat the house edge?
No. Strategies change how wins and losses are spread over time, but every bet still loses the house edge on average.
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