To count cards in blackjack, give every card a simple value as it is dealt, keep a running total in your head, and use that total to judge whether the cards left in the shoe favor you or the dealer. With the Hi-Lo system, cards 2 to 6 count +1, cards 7 to 9 count 0, and tens and aces count -1. In multi-deck games you then divide the running count by the number of decks left to get the true count, which tells you when to bet more and when to bet the minimum.
Counting does not guarantee a profit. At best it turns a small house edge into a small player edge over many hours of play, with large swings along the way. This guide walks through the method step by step, shows how the count changes your bets and a few key decisions, and explains the U.S. legal position.
| Card counting basics | What you need to know |
|---|---|
| Best beginner system | Hi-Lo |
| Cards 2 to 6 | +1 |
| Cards 7 to 9 | 0 |
| 10, J, Q, K, A | -1 |
| Running count | Total of all card values seen since the shuffle |
| True count | Running count divided by estimated decks remaining |
| Rough effect | Each +1 of true count moves the edge about 0.5% toward the player |
| Works best with | Hand-shuffled shoes, deep penetration, 3:2 blackjack payouts |
| Guaranteed winnings? | No |
| U.S. legal issue | Mental counting is treated differently from using electronic devices |
What card counting actually does
A counter does not memorize every card. Instead, the count tracks the balance between low and high cards that have already been played, which tells you roughly what is left. When many low cards are gone, the remaining shoe is rich in tens and aces, and that helps the player in several ways:
- Blackjacks become more frequent, and the player is paid 3:2 on them while the dealer only wins even money.
- The dealer must hit stiff hands (12 to 16) and busts more often when tens are plentiful.
- Doubling down on 10 and 11 succeeds more often.
- Insurance becomes a good bet once the shoe is rich enough in tens.
Low-card-rich shoes do the opposite, helping the dealer complete weak hands. Blackjack is unusual among casino games because cards already dealt change the odds of the hands that follow, which is what makes counting possible at all.
What you need before learning the count
You need a solid grasp of blackjack rules and, above all, basic strategy: the mathematically correct way to hit, stand, double and split for each hand against each dealer upcard. Basic strategy alone brings the house edge down to roughly half a percent in a game with good rules. Counting on top of poor decisions wastes most of the benefit.
Practice with a real deck at home or with free casino games and blackjack trainers before any money is involved. Treat the count as a statistical tool, not a way to predict the next card.
How to count cards with the Hi-Lo system: 5 steps
- Learn the values. 2, 3, 4, 5 and 6 are +1. 7, 8 and 9 are 0. 10, J, Q, K and A are -1.
- Start at zero after each shuffle. Hi-Lo is a balanced count, so a full deck adds up to exactly zero.
- Count every exposed card. Your cards, other players’ cards, and the dealer’s cards, including the hole card when it is revealed. Do not reset between hands.
- Estimate decks remaining. Glance at the discard tray and subtract from the total number of decks in the shoe.
- Convert to a true count. Divide the running count by the decks remaining, then use the true count for betting and strategy changes.
Running count vs true count, with examples
Say the first six cards are 5, king, 3, 8, ace and 6. Their values are +1, -1, +1, 0, -1 and +1, so the running count is +1. A positive count means more low cards have gone, so the rest of the shoe is slightly richer in high cards.
The same running count means different things in different shoes. A running count of +6 with three decks left is a true count of +2. With two decks left it is +3, and with six decks left only +1. Converting to the true count puts every situation on the same scale. Most players round down or to the nearest half deck, and that is accurate enough.
Using the count: bet sizing
The main way counters gain an edge is by betting more when the true count is high and the minimum when it is neutral or negative. A widely used rule of thumb is that each +1 of true count shifts the edge about 0.5% toward the player, so in a typical game the player only gets an advantage from around +1 or +2 upward. A simple, illustrative betting ramp might look like this:
| True count | Approximate situation | Example bet (in units) |
|---|---|---|
| +1 or lower | House still has the edge | 1 unit (table minimum) |
| +2 | Roughly break-even to slight player edge | 2 units |
| +3 | Modest player edge | 4 units |
| +4 | Stronger player edge | 6 units |
| +5 or higher | Best situations | 8 units |
Exact break-even points depend on the rules, and bigger bet spreads attract attention from casino staff. Unit size should be a small fraction of a dedicated bankroll, because even a correct player edge produces long losing runs.
Using the count: key strategy changes
Experienced counters also change a handful of basic strategy plays at certain true counts. The best known set is the “Illustrious 18” from Don Schlesinger’s book Blackjack Attack. The most valuable plays for a beginner are:
- Insurance: take it at a true count of +3 or higher; otherwise never.
- 16 vs dealer 10: stand at a true count of 0 or higher instead of hitting.
- 15 vs dealer 10: stand at +4 or higher.
- 12 vs dealer 3: stand at +2 or higher; 12 vs dealer 2, stand at +3 or higher.
Add these only once your count and basic strategy are automatic.
Hi-Lo compared with other counting systems
| System | Card values | True count needed? | Difficulty |
|---|---|---|---|
| Hi-Lo | 2 to 6: +1, 7 to 9: 0, 10 to A: -1 | Yes | Beginner |
| KO (Knock-Out) | Like Hi-Lo, but 7 is also +1 | No, it is unbalanced | Beginner |
| Hi-Opt I | 3 to 6: +1, tens: -1, 2 and A: 0 | Yes, plus a side count of aces | Intermediate |
| Omega II | Multi-level values from +2 to -2 | Yes | Advanced |
More complex systems gain a little accuracy but cost speed and increase errors. For most players, a mistake-free Hi-Lo beats a sloppy advanced count.
Game conditions that make or break counting
- Penetration: how deep into the shoe the dealer goes before shuffling. Around 75% or more is considered good; shallow penetration means high counts rarely appear.
- Blackjack payout: 3:2 games are essential. 6:5 payouts add well over a full percent to the house edge, more than counting can usually overcome.
- Continuous shuffling machines: cards are returned to the machine after each round, so counting is useless.
- Number of decks: fewer decks make each card matter more, although single-deck games often come with worse rules.
Practice drills for beginners
- Turn over a shuffled deck one card at a time and keep the count. You should finish at zero. Aim for under 30 seconds without errors.
- Hide one card at the start, count the rest, and work out whether the hidden card was high, low or neutral from your final count.
- Count cards in pairs so that a high and low card cancel instantly.
- Practice deck estimation with stacks of half and quarter decks.
- Add noise and conversation to mimic a casino floor.
Common card counting mistakes
Chasing speed before accuracy is the most common error, since one missed card distorts everything after it. Other frequent mistakes include using the running count instead of the true count in a shoe game, skipping basic strategy, playing 6:5 or continuous shuffle tables, and betting too large a share of the bankroll after a few wins.
Does card counting work in online blackjack?
Not in standard RNG blackjack, where the software effectively shuffles between hands. Some live-dealer tables use physical shoes, but they are usually cut shallow, which limits counting opportunities. Check how any game handles its shoe before assuming counting applies.
Is card counting illegal in the United States?
Counting cards in your head is generally not treated as cheating under U.S. law, because you are only using information visible to everyone at the table. Using devices is a different matter. In Nevada, NRS 465.075 makes it unlawful to use or possess a device to help project the outcome of a game, keep track of cards played, or analyze probabilities. A phone app or hidden counter at the table is therefore far riskier than mental arithmetic.
Casinos can still respond to counters. In many states, private casinos may ask advantage players to stop playing blackjack, flat bet, or leave. New Jersey is a notable exception in one respect: in Uston v. Resorts International Hotel (1982), the state Supreme Court held that Atlantic City casinos could not simply exclude skilled counters, although casinos there can still use countermeasures such as shuffling more often. Always follow staff instructions. You can read more in our gaming section.
Bankroll and responsible play
No count removes variance. Set a fixed budget you can afford to lose, never chase losses, and never gamble with money needed for rent, bills or debt. If gambling stops being fun, U.S. players can call the 1-800-GAMBLER helpline for confidential support. You must also meet the legal gambling age where you play, which is 21 in most U.S. casinos.
Frequently asked questions
How do you count cards as a beginner?
Use the Hi-Lo system: +1 for 2 to 6, 0 for 7 to 9, and -1 for tens and aces. Practice with one deck until you reliably finish at zero.
What is the difference between the running count and true count?
The running count is the total of all card values seen. The true count divides that total by the decks remaining, so it means the same thing in any size of shoe.
When should a card counter raise their bet?
Typically once the true count reaches about +2, when the edge starts to shift toward the player. Exact points depend on the table rules.
Is counting cards illegal?
Mental counting is generally not illegal in the U.S., but using devices to track cards is prohibited in Nevada under NRS 465.075, and casinos may use countermeasures or restrict play.
Can card counting guarantee a win?
No. It can create a small edge over many hands, but short-term losses are common and substantial.
This article is general information, not legal or financial advice. Gambling involves risk; play only where it is legal and within your limits.
