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This article is for anyone who plays online casino games and wants to understand why the house always wins in the long run, and what that edge actually looks like across different games.
The house edge is the percentage of every bet that the casino expects to keep over time. Not on your next spin or your next hand - variance means you can win or lose in the short term. But over thousands of bets, the edge grinds everyone down to the same place. It's not luck. It's just math.
Roulette - The Clearest Example
European roulette has 37 numbers - 0 through 36. If you bet on a single number and win, the casino pays you 35-1.But there are 37 possible outcomes. The true odds of hitting your number are 36-1. The casino pays you 35-1. That one-unit gap is the house edge. It works out to 2.7% of every bet you make.
Here's what that means in practice. You bet £10 on a single number 37 times, covering every spin. You'll win once and lose 36 times. Your one win pays £350. Your 36 losses cost £360. You're down £10 on £370 wagered. That's 2.7%.
American roulette adds a second zero - 00. Now there are 38 numbers but the payout is still 35-1. The house edge jumps to 5.26%. Same game, worse odds, just because of one extra pocket on the wheel.
The casino doesn't need you to lose every spin. They just need you to keep playing, because that 2.7% or 5.26% compounds over time. Play long enough and the edge guarantees they win. Not might win. Will win.
Blackjack - Where Strategy Actually Matters
Blackjack is different because your decisions affect the outcome.With perfect basic strategy - hitting, standing, doubling, and splitting exactly when the math says to - the house edge is around 0.5% in most games. That's tiny compared to roulette. But most players don't use perfect strategy. They hit when they should stand, they don't double when they should, they make gut decisions based on what feels right. The house edge against a typical player is probably 2-3%.
The 0.5% edge assumes you're playing perfectly every hand. No mistakes. No hunches. Just following the strategy chart exactly as the math dictates. Even then, the casino still has an edge. You're just minimizing how much you're giving up.
Card counting can flip the edge to the player's side, maybe 1-2% if you're good at it. That's why casinos ban counters. The house edge is built into the rules, but counting exploits the fact that the deck composition changes and creates spots where the player has the advantage. Online casinos use continuous shuffle machines or shuffle after every hand, which makes counting impossible. The edge stays with the house.
Slots - The Worst Game in the Casino
Slot machines are brutal. House edge typically runs 2-15% depending on the game and the casino.You can't calculate the edge yourself because you don't know the reel weightings - how often each symbol appears. The casino programs that into the machine. Two identical-looking slots sitting next to each other can have completely different edges. You've got no way to know which is which.
The advertised RTP - return to player - is just the inverse of the house edge. A 95% RTP means a 5% house edge. But even that's misleading because it's calculated over millions of spins. Your session of 100 spins means nothing. You could hit a bonus round and walk away up 200%. You could lose 20 bets in a row. The variance is massive. The edge only matters long-term.
Progressive jackpot slots are worse. The jackpot looks huge, but the base game RTP is usually terrible - sometimes 85-88% - because the casino is funding that jackpot from everyone's losses. You're paying for someone else's eventual big win, and statistically that someone isn't you.
Other Games and Their Edges
Craps has some of the best odds in the casino if you stick to the right bets. Pass line is 1.41% house edge. Don't pass is 1.36%. The odds bet - the one you can make after the point is set - has zero house edge. It's a fair bet. But you can't make it without making the pass line bet first, so you're still paying the edge on that portion.The proposition bets in craps are terrible. Any seven is 16.67% house edge. Hard ways are 9-11%. These are sucker bets. The casino puts them in the middle of the table with big payouts to tempt people who don't understand what they're giving up.
Baccarat is around 1.06% on banker, 1.24% on player. Simple game, low edge, which is why high rollers like it. The tie bet is 14.36% edge - avoid it completely.
Video poker can get down to 0.5% or even lower with perfect strategy, similar to blackjack. But perfect strategy in video poker is complicated. Most people play poorly and the edge creeps up to 2-3%.
Why Online Casinos Are No Different
People think online casinos might be rigged because you can't see physical cards or wheels. They're not rigged. They don't need to be.The house edge built into the rules is enough. An online roulette wheel with a random number generator has the same 2.7% edge as a physical wheel in Vegas. The math doesn't change. The casino makes money the same way - volume and time. Get enough people playing long enough and the edge does its job.
Online casinos actually have lower operating costs than physical casinos. No building, no dealers, no floor staff. They can offer better RTPs and still make massive profits because their margins are so high and their volume is enormous. A 2% house edge on millions of pounds wagered per day is still huge money.
Live dealer games online are the same as physical casino games. Real cards, real wheels, real dealers, just streamed to your screen. Same rules, same edge. The technology is different but the math is identical.
The Compounding Problem
Every bet you make pays the house edge again. This is what kills people.You sit down with £100. You bet £10 per spin on roulette. You win some, you lose some, variance bounces you around. But every spin, you're paying that 2.7% edge. After an hour you might have £80 left. After two hours maybe £60. The edge doesn't hit you all at once - it bleeds you slowly.
The more hands you play, the more certain it is that you'll lose. That's not pessimism, that's just statistics. Short sessions with high variance give you a chance to get lucky and walk away up. Long sessions guarantee the edge catches up to you.
This is why "systems" don't work. Martingale - doubling your bet after every loss - doesn't beat the house edge. You're still paying 2.7% per spin. You're just risking more money to grind out small wins until you hit a losing streak that wipes you out. Same with any other progression system. The edge is still there on every single bet.
Games You Should Avoid
Anything with a house edge above 5% is just donating money.Keno is often 25-40% house edge. It's basically a lottery and the casino keeps an absurd percentage. You're better off buying actual lottery tickets, and lottery tickets are already terrible bets.
Wheel of Fortune / Big Six has edges up to 24%. You spin a wheel, you win or lose based on where it lands. No skill, no strategy, just a massive edge against you.
Side bets in blackjack and baccarat are usually 3-8% edge or worse. Insurance in blackjack is a 7.4% edge against you. Perfect pairs, 21+3, lucky ladies - all of these are higher edge than the base game. The casino offers them because people like the big payouts, but you're paying heavily for that chance.
Slot tournaments are interesting because you're competing against other players, not the house. But the casino takes a rake from the prize pool, so there's still an edge. Just a different structure.
Can You Actually Win?
In the short term, yes. Variance means anything can happen over 10 or 50 or 100 bets.I've seen people walk into a casino with £50, hit a slot bonus round, cash out £800, and leave. That's not skill, that's just variance landing in their favor. The casino doesn't care. They know for every person who runs hot and leaves, ten more will run cold and chase their losses until they're broke.
Long term? No. You can't beat the house edge with luck. It's mathematically impossible. The only way to win long-term is to find an exploitable game - card counting in blackjack, or certain video poker variants with promotions that push the RTP above 100% - and those opportunities are rare and usually get shut down quickly.
The smart play is to understand what you're paying for. If you enjoy playing and you're treating it as entertainment, fine. Budget what you can afford to lose, play games with low house edge, and don't chase losses. But don't convince yourself you're going to beat the casino long-term unless you've found something genuinely exploitable, and even then you're probably wrong.
Why Casinos Love Gamblers Who Don't Understand This
Most casino players have no idea what house edge means or how it works.They think roulette is "due" to hit red after six blacks. They think they're unlucky when they lose over time. They think there's a system or pattern that can beat the games. The casino doesn't need to cheat these people. These people cheat themselves by not understanding the math.
The players who understand house edge either play games with low edges and quit while ahead, or they don't play at all because they realize it's not beatable. The casino makes their money from everyone in between - the people who play for hours, who chase losses, who believe they can beat variance with a system.
That's the entire business model. Not deception. Not rigging. Just offering games with a built-in mathematical advantage and letting human psychology do the rest. People want to believe they can win. The house edge guarantees most of them won't.
FAQ
Q: Is online casino RTP the same as land-based casino RTP?Usually yes, sometimes better. Online casinos have lower costs so they can offer better RTPs and still be profitable. But it varies by casino and by game. A 96% RTP slot online is equivalent to a 4% house edge. That's better than most land-based slots which often run 88-92% RTP. Always check the game info screen for the stated RTP.
Q: Can the casino change the RTP on the fly to make me lose?
No. Licensed online casinos use certified RNG software that's audited by third parties. The RTP is set in the game code and can't be changed during play. What feels like the casino "tightening up" when you're winning is just variance. You're experiencing the normal fluctuations of a game with a house edge. It's not personal and it's not manipulated.
Q: If I play a game with 1% house edge instead of 5%, does that mean I'll lose five times slower?
Roughly, yes. The house edge is the percentage of your total wagered amount that the casino expects to keep. If you bet £1,000 total on a 1% edge game, they expect to keep £10. On a 5% edge game, they expect to keep £50. But variance means your actual results will bounce around that expectation. You could still lose faster on the 1% game if you're unlucky, or slower on the 5% game if you're running hot. The edge just determines the long-term average.
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