Advantage Play & Game Integrity

Card counting

Also called

Counting cards³

Applies to

Blackjack; related methods exist for baccarat¹⁸

Common point system

2–6 = +1, 7–9 = 0, 10–A = −1; count starts at 0²⁶

Player edge

Up to about 2% with card counting, vs. a house edge of 0.5–1% with basic strategy⁶⁷

Key points

• The counter tracks exposed cards as a running total, then converts it to a true count by dividing by decks remaining.¹⁶
• When the true count is high (deck rich in high cards), the player increases bets and may alter playing decisions; when low, bets are reduced.¹⁷
• Card counting is not illegal, but casinos can ban counters under private-property rights.¹
• Hi-Lo is a specific system with values 2–6 = +1, 7–9 = 0, 10–A = −1; many other systems exist.⁹⁷
• The technique requires practice but is learnable; it is not a memory trick but a disciplined method of tracking ratios.⁶

How card counting works

1. Assign a point value to each card rank (e.g., 2–6 = +1, 7–9 = 0, 10–A = −1).²
2. Start the running count at 0 at the beginning of a fresh shoe or deck.⁶
3. Add or subtract the point value of each card as it is exposed; this gives the running count.¹
4. Divide the running count by the number of decks remaining to get the true count.⁷
5. When the true count is high, increase bets and adjust basic strategy; when low, bet the minimum.¹

Is card counting illegal?

Card counting is not illegal under criminal law. It is a mental skill, not a device or a cheat.¹ However, casinos are private businesses and can refuse service to anyone they suspect of counting. Many casinos train staff to spot counters and will ban them from the premises if caught.⁴

The confusion about legality often comes from the fact that casinos treat counting as undesirable. Some jurisdictions have laws against using devices to aid counting, but the act itself is not a crime.¹

Common questions

Where this term is used

• Advantage play

Not the same as

• Blackjack card counting — the same core idea but the broader term 'card counting' refers to the general technique rather than the blackjack-specific use¹²
• Hi-lo card counting — a specific card-counting system with values 2–6 = +1, 7–9 = 0, 10–A = −1, whereas card counting is the general method⁹⁷

Related terms

Sources

1. Card counting en.wikipedia.org Provides the general definition, application, and legality of card counting.
2. Blackjack en.wikipedia.org Supports the common point system values and the house edge comparison.
3. Counting cards - Wikipedia en.wikipedia.org Confirms the alternative name 'counting cards' and that poker is not a standard context.
4. MIT Blackjack Team - Wikipedia en.wikipedia.org Supports the point that casinos ban counters, referencing the MIT Blackjack Team.
5. Hole carding en.wikipedia.org Supports that poker is not the usual context for card counting.
6. Card Counting in Blackjack - Introduction & Basics wizardofodds.com Provides the point system, true count calculation, and player edge figures.
7. Introduction to the High-Low Card Counting Strategy wizardofodds.com Supports the Hi-Lo system details and the player edge from counting.
8. Card Counting in Baccarat wizardofodds.com Supports that card counting can apply to baccarat.
9. カードカウンティング jp.wizardofodds.com Supports the Hi-Lo system values as a specific system distinct from general counting.

Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.