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What Card Counting Is and Why It Rarely Helps in Online Blackjack
Card counting means keeping track of the cards already dealt from the shoe – the box the cards are dealt from – to tell when many tens and aces are left. It is generally not a crime, but casinos can refuse to deal to you, and online it rarely works because most digital games reshuffle every round and live dealer games often reshuffle early.
- What card counting is
- Why the remaining cards matter
- Why casinos dislike card counting
- Is card counting illegal?
- Why card counting rarely works online
- What actually lowers your cost
01What card counting is
Card counting is keeping track of the cards that have already been played. The player does it in their head, using only the cards that are face up on the table.
These cards are face up on the table. A counter remembers what kind of cards they are and works out what kind of cards are still left in the shoe.
- It is: remembering the cards you can see.
- It is not: seeing the dealer's hidden card.
- It is not: knowing the next card. The next card is still random.
- It is not: a device or software. Using those is a different thing.
This page explains the idea only. It does not teach a counting system.
02Why the remaining cards matter
A ten-value card is any 10, J, Q or K. When many ten-value cards and aces are left in the shoe, the game changes in a few ways.
- More blackjacks. A blackjack is an ace plus a ten-value card as your first two cards.
- Blackjack pays you more. Your blackjack pays 3:2. A dealer blackjack only takes your bet.
- The dealer busts more often. The dealer must take a card on 12 to 16. A ten-value card makes those totals go over 21.
- Doubles land better. When you double on 10 or 11, a ten-value card gives you 20 or 21.
In a normal shoe, a paid blackjack comes about once every 22 hands. The picture below shows what a 10 bet pays for a blackjack.
The chart below shows how often the dealer busts with each up card – the dealer's card that faces up. These numbers are for a normal shoe, before any cards are tracked, and are counted before the dealer checks for blackjack.
Dealer up card along the bottom; how often the dealer goes over 21 above each bar (6 decks, dealer hits soft 17, before any check for blackjack).
With a 6 up, the dealer busts about 43.9% of the time. With an ace up, the dealer busts about 13.9% of the time.
When mostly small cards are left, the dealer busts less often and you get fewer blackjacks.
03Why casinos dislike card counting
A player who counts bets more when the shoe has many tens and aces left. That player bets less, or stops, when it does not.
A counter bets more only when the cards left favor the player. That is what casinos watch for.
These small cards are already dealt. The shoe now has more tens and aces left than before.
- The house edge – the share of each bet the casino keeps on average – is part of every bet you make.
- Changing your bet without knowing the cards does not change the house edge. See betting systems for more.
- Casinos watch for big changes in bet size between hands.
If a casino asks you to stop playing blackjack, it is their decision to make. Leave politely and do not argue with staff.
04Is card counting illegal?
Counting cards in your head is generally not a crime. You are only using what you see on the table.
Rules depend on where you live, and casinos may refuse service. A casino can choose who it deals to.
| Where | What can happen |
|---|---|
| At a casino table | Staff can stop dealing to you or ask you to leave. |
| At an online casino | The site can limit your bets or close your account under its own terms. |
| Devices and software | Using a tool to track cards is treated very differently from counting in your head. Do not do it. |
Before you play for money, check what is allowed where you live. The responsible gambling page has more on playing safely.
05Why card counting rarely works online
Online blackjack comes in two main types. Neither one gives a counter much to work with.
| Game type | How the cards are shuffled | Does counting help? |
|---|---|---|
| Digital blackjack | Software usually shuffles a fresh shoe before every round | Usually no – the cards you saw are back in the shoe |
| Live dealer blackjack | Real cards on camera, but the shoe is often cut early | Rarely – many cards are never dealt before the reshuffle |
Digital games use a random number generator – software that picks the cards. When the shoe is reshuffled every round, past cards tell you nothing.
Live dealer games use a cut card – a plastic card placed in the shoe that tells the dealer when to reshuffle. When it is placed early, a large part of the shoe is never played.
In online blackjack, focus on playing each hand correctly. In a game that reshuffles every round, the cards from the last hand do not change the next one.
06What actually lowers your cost
Two things lower the house edge in every online game: basic strategy and good table rules. Basic strategy is the best move for each hand against each dealer up card.
Here is one row of the basic strategy chart. With hard 16, you stand against a dealer 2 to 6 and hit against 7 to A.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| S | S | S | S | S | H | H | H | H | H |
Against a dealer 10, hitting hard 16 averages −0.535 per bet and standing averages −0.540. Both lose on average, but hitting loses less.
Table rules matter too. This table shows the house edge with perfect basic strategy.
| Table rules | House edge |
|---|---|
| 6 decks, blackjack pays 3:2, dealer hits soft 17 | 0.62% |
| Same, but dealer stands on soft 17 | 0.40% |
| Same as first row, plus late surrender | 0.53% |
| Same as first row, but blackjack pays 6:5 | 1.98% |
| Same as first row, but blackjack pays 1:1 | 2.88% |
The payout for blackjack makes the biggest difference. See 6:5 blackjack for more.
Learn the chart with the blackjack trainer and pick tables that pay 3:2. Basic strategy lowers the house edge, but it does not remove it.
Questions people ask
What is card counting in blackjack?
Card counting is keeping track of the cards already dealt to tell when many tens and aces are left in the shoe. It is done in your head, using only the cards you can see.
Is card counting illegal?
Counting cards in your head is generally not a crime. Rules depend on where you live, and casinos may refuse service or ask you to leave.
Does card counting work in online blackjack?
Usually not in digital games. Most digital games reshuffle the cards every round, so the cards you saw tell you nothing about the next hand.
Can you count cards in live dealer blackjack?
Rarely. Live dealer games often place the cut card early, so a large part of the shoe is reshuffled before it is dealt.
Is card counting cheating?
Counting in your head uses only the cards on the table, so it is not the same as cheating. Using a device or software to track cards is different and you should not do it.
What lowers the house edge if counting does not work online?
Play basic strategy on every hand and choose tables where blackjack pays 3:2. With standard rules and perfect basic strategy, the house edge is about 0.62%.
Where the numbers come from
Every number on this page is worked out by our blackjack engine for the rules stated next to it, with perfect basic strategy. Unless a rule is named, the rules are 6 decks, dealer hits soft 17, double after split allowed, no surrender, the dealer checks for blackjack, and blackjack pays 3:2.