How card counting works: the Hi-Lo system, explained simply

Card counting isn't about memorizing every card. It's keeping one running number in your head that tells you when the cards left in the shoe favor you instead of the casino.

Learning only. True Count is a practice tool with no real money. Counting in your head isn't a crime in most places, but casinos are private businesses and can ask counters to stop playing or leave, and using any device to count at a casino is illegal in many places. If you ever gamble, only use money you can afford to lose. See our responsible gambling page.

Why counting works

When lots of small cards have been played, the cards left are rich in 10s and aces. That's good for you: you get more blackjacks (which pay 3 to 2), your doubles land better, and the dealer, who has to hit stiff hands, busts more often. Counting tells you when that's happening.

Step 1: card values

In the Hi-Lo system, every card gets one of three values:

Cards	Value	Why
2, 3, 4, 5, 6	+1	Small cards leaving the shoe help you
7, 8, 9	0	Neutral. Ignore them.
10, J, Q, K, A	−1	Big cards leaving the shoe hurt you

Step 2: the running count

Start at 0 when the dealer shuffles. Add each card's value as it appears and keep only the total in your head. For example, a 5, a king, a 2 and a 6 come out: +1, −1, +1, +1, so the running count is +2. Good counters add cards in pairs: a big card and a small card cancel to 0.

Step 3: the true count

A running count of +6 means a lot more with 1 deck left than with 6. So you divide the running count by the number of decks still in the shoe, which you estimate by looking at the discard tray, and round down.

Running count	Decks left	True count
+6	6	+1
+6	2	+3
+9	2	+4 (4.5 rounds down)

Step 4: bet with the count

Most of a counter's edge comes from betting more when the true count is high. Each point of true count is worth roughly half a percent to the player, so at +1 or below the casino still has the edge and you bet the minimum. A simple bet ramp, where 1 unit is your smallest bet:

True count	Bet
+1 or less	1 unit
+2	2 units
+3	4 units
+4	6 units
+5	8 units
+6 or more	12 units

Step 5: index plays

At certain counts, a few basic strategy plays change. The best-known set is the "Illustrious 18". The most valuable ones:

Hand	Change to	When the true count is
Insurance	Take it	+3 or higher
16 against a 10	Stand	0 or higher
15 against a 10	Stand	+4 or higher
10 against a 10	Double	+4 or higher
12 against a 3	Stand	+2 or higher
12 against a 2	Stand	+3 or higher

The honest reality

Even perfect counting only gives a small edge, around 1% for a good counter, and results swing a lot from session to session. Casinos also fight back with continuous shuffling machines and by shuffling early. That's why True Count treats counting as a skill to learn and a fun mental challenge, not a way to make money.

Practice it

The True Count trainer takes you from card values to a full table simulation in 11 lessons, with drills like counting down a deck against the clock.

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New to blackjack strategy? Start with the basic strategy chart.