Card Counting in Blackjack
Card counting is a strategy that tracks the ratio of high to low cards remaining in the deck. When the deck is rich in high cards (10s and Aces), the player has an advantage. Counters bet more in these situations.
How Card Counting Works
The most common system is Hi-Lo:
| Cards | Count Value |
|---|---|
| 2, 3, 4, 5, 6 | +1 |
| 7, 8, 9 | 0 |
| 10, J, Q, K, A | -1 |
As cards are dealt, you keep a running count. When the count is high (many low cards dealt), more high cards remain—favoring the player.
Why High Cards Favor Players
- More blackjacks (paid 3:2)
- Better doubling results (more 10s to draw)
- Dealer busts more (must hit stiff hands)
Is Card Counting Legal?
Yes, card counting is legal. You're using your brain, not a device. However:
- Casinos are private property
- They can ask you to leave
- They can ban you from playing blackjack
- They cannot arrest you for counting
Requirements for Successful Counting
- Perfect basic strategy — counting is worthless without it
- Sufficient bankroll — variance is extreme
- Good deck penetration — casinos that shuffle early neutralize counting
- Betting spread — you must bet more when the count favors you
- Cover — casinos watch for count patterns
Why Basic Strategy Comes First
Card counting adds a small player edge (~0.5-1.5%) on top of basic strategy. If you don't know basic strategy perfectly, you're giving back more than counting gains.
Master basic strategy first before considering card counting.
The Reality
Modern casinos use multiple decks, frequent shuffling, and sophisticated surveillance. Successful card counting requires significant skill, practice, and discipline—with modest expected returns.
For recreational players, perfect basic strategy is the best approach.