How to count cards in blackjack
Updated 9 November 2026 · Blackjack Theory
Card counting is how skilled players turn blackjack from a game the house wins into one they can beat. It doesn’t take a photographic memory: with the Hi-Lo system you only ever add one, subtract one or do nothing. Here is the whole method, step by step, with worked examples.
Why counting cards works
The dealer must hit until 17; you get to choose. When the remaining shoe is rich in tens and aces, you get more blackjacks (paid 3 to 2), your doubles land more often, and the dealer busts more with stiff hands. When it's full of small cards, the dealer is the one who benefits. Counting tells you which situation you're in, so you can bet more when the shoe favours you.
Step 1: Learn the Hi-Lo card values
A deck has 20 low cards and 20 high cards, so a full deck adds up to exactly zero. That makes Hi-Lo a balanced count, and gives you a self-check: count down a full deck and you should finish on 0.
Step 2: Keep a running count
Start at 0 after the shuffle and add each card's value as it's dealt. Here's an example:
| Card | Value | Running count |
|---|---|---|
| K | −1 | −1 |
| 5 | +1 | 0 |
| 3 | +1 | +1 |
| 9 | 0 | +1 |
| A | −1 | 0 |
| 6 | +1 | +1 |
| 2 | +1 | +2 |
| 10 | −1 | +1 |
| 7 | 0 | +1 |
| 4 | +1 | +2 |
Speed comes from practice. Experienced counters cancel pairs out (a 5 and a king together are 0) and count the whole table at once rather than card by card.
Step 3: Convert to the true count
A running count of +6 is huge with one deck left and minor with five. To compare, divide by the number of decks still to be dealt, which you estimate from the discard tray. Then round toward zero.
| Running count | Decks left | Exact | True count |
|---|---|---|---|
| +6 | 3 | +2 | +2 |
| +9 | 2 | +4.5 | +4 |
| −5 | 2.5 | −2 | −2 |
| +7 | 4 | +1.7 | +1 |
Step 4: Bet with the count
Perfect basic strategy still leaves the house a small edge. Each +1 of true count moves roughly 0.5% toward you, so the game typically turns in your favour around +1 to +2. A simple 1–8 betting ramp looks like this:
| True count | Bet |
|---|---|
| 0 or less | 1 unit |
| +1 | 1 unit |
| +2 | 2 units |
| +3 | 4 units |
| +4 | 6 units |
| +5 or more | 8 units |
Step 5: Use the count to change your plays
At certain counts the best play changes: standing on 16 against a 10 at 0 or higher, for example. The most valuable of these "index plays" are known as the Illustrious 18 and Fab 4.
A practice plan
- Get basic strategy perfect first; see the basic strategy chart.
- Drill card values until you say them without thinking.
- Count down a single deck; aim for under 30 seconds and finish on 0.
- Practise running counts with cards dealt at speed, then convert to true counts.
- Add counting to real play: keep the count while making every decision.
Frequently asked questions
Is card counting illegal?
No. Card counting is simply keeping track of cards you can see, and it is legal. Casinos are private businesses, though, and can ask a player they suspect of counting to stop playing blackjack or leave.
How much of an edge does card counting give?
Each +1 of true count shifts the odds roughly 0.5% toward the player. With good basic strategy and a sensible bet spread, a skilled counter typically gets an overall edge of around 0.5–1.5%, depending on the rules, penetration and spread.
Does card counting work online?
Usually not. Most online blackjack reshuffles after every hand or uses a continuous shuffler, so the count never builds up. Some live-dealer games deal from a shoe, but penetration is often poor.
What is the easiest card counting system?
Hi-Lo is the most widely used and one of the easiest: low cards (2–6) count +1, high cards (10s and aces) count −1, and everything else is 0. It is a balanced count, so a full deck adds up to zero.
What is the difference between the running count and the true count?
The running count is the total of every card value seen since the shuffle. The true count divides that by the number of decks left to be dealt, so it means the same thing early or late in the shoe. Betting and playing decisions use the true count.