Is Online Blackjack Rigged? How Shuffling Really Works
A fairly dealt online blackjack game shuffles the whole shoe once, before any cards are dealt, and then deals from the top. Once the order is fixed, the game can't choose which card you get next. Losing streaks that feel rigged are a normal part of a game you lose about 48% of hands in, and you can check a game's fairness yourself against the numbers in this article.
This article explains how House21 deals, and how to tell a fair game from a suspicious one anywhere.
How House21 shuffles and deals
- Six standard decks go into one shoe: 312 cards, 24 of each rank.
- The shoe is shuffled once, using the Fisher-Yates method: going from the last card to the first, each card swaps places with a randomly chosen card at or before it. Every possible order of the 312 cards is equally likely.
- The random numbers come from Node.js
crypto.randomInt, the operating system's cryptographically secure generator. "Secure" here means the next number can't be worked out from earlier ones, so seeing cards dealt doesn't let anyone predict the rest of the shoe. - Cards are dealt in order from the shoe, to every seat and to the dealer.
- When fewer than 52 cards remain before a round, a fresh shoe is built and shuffled.
The important property is step 4. The order is set before the round starts, so there is no point at which code decides "this player gets a 10". Every player at the table, and the dealer, draws from the same sequence.
"But I lost eight hands in a row"
That happens, and more often than people expect. With basic strategy you win about 43% of hands, lose about 48% and push the rest. Treat a push as nothing, and the chance of losing any given hand you don't push is about 52.5%.
| Streak | Chance it starts on a given hand | Chance of at least one in 500 hands |
|---|---|---|
| 5 losses in a row | 1 in 25 | Practically certain |
| 8 losses in a row | 1 in 173 | About 71% |
| 10 losses in a row | 1 in 629 | About 28% |
Pushes are treated as neither breaking nor extending a streak; the 500-hand figures come from 20,000 simulated sessions.
A long losing run is the cost of a game where each hand is close to a coin flip. A game that never produced them would be the suspicious one.
The gambler's fallacy, and the part of it that isn't quite a fallacy
The gambler's fallacy is the belief that a result is "due" because it hasn't happened in a while. In roulette it is pure fallacy: every spin is independent, so red is no more likely after ten blacks.
Blackjack is slightly different. Cards are dealt without replacement, so a shoe that has given out lots of low cards really does have more high cards left. That is the whole idea behind card counting. But the effect is small, it depends on which cards came out, not on whether you won or lost, and it resets with every new shoe. A losing streak by itself tells you nothing about the next hand.
Numbers you can check yourself
If you think a game is unfair, don't trust a feeling. Count. Over a few hundred hands these numbers should land close to the figures below for a 6-deck game where the dealer stands on 17.
| What to count | Expected in a fair game | Where the number comes from |
|---|---|---|
| Your blackjacks | About 1 hand in 21 (4.7%) | Probability of an ace + a 10 from a 6-deck shoe |
| Dealer busts when showing a 6 | About 42% | Exact calculation |
| Dealer busts when showing a 10 | About 23% | Same |
| Hands won, lost, pushed (basic strategy) | 43% / 48% / 9% | 20 million simulated hands at House21's rules |
A few hundred hands is enough to spot a big problem, like a dealer who busts from a 6 one time in five. It is not enough to spot a difference of a percent or two; that takes tens of thousands of hands.
Why would a free game rig anything?
It's a fair question to ask of any game, including ours. House21 sells nothing: chips are virtual, can't be bought and can't be cashed out. A free game does want you to keep playing, and the honest way to do that is with rewards you can see, like daily bonuses and levels, not with the cards. A game that quietly made you lose more would just make people quit sooner.
What the shuffle can't do is make blackjack a winning game. With perfect basic strategy the house keeps about 0.5% of every bet over time. That edge is in the rules, not the deck: you act first, so when you bust you lose even if the dealer busts afterwards.
Red flags in any online blackjack game
- The rules aren't published, or blackjack pays 6 to 5 instead of 3 to 2. The 6 to 5 rule alone costs you about 1.4% of every bet.
- The dealer's bust rate from a 5 or 6 is far below 40% over hundreds of hands.
- "Continuous shuffling" isn't disclosed, yet results seem to react to your bet size.
- The site won't say how cards are shuffled at all.
Common questions
Does the game know my bet before it deals? Bets close before the deal, but it doesn't matter: the shoe was shuffled before the round started.
Can other players' choices make me lose? No. They change which cards you get, but not in a direction anyone can predict.
Why do near-misses feel so common? Because they're memorable. Your brain stores a 20 that lost to a 21 more vividly than ten quiet wins. More on that in Why "one more hand" is hard to resist.
See the numbers for yourself at a free table in the lobby.