How to Count Cards Playing Blackjack: The Hi-Lo Method Step by Step

To count cards in blackjack, you keep a running total as cards are dealt. Low cards (2–6) add one, high cards (10s, picture cards and aces) take one away, and 7–9 count as zero. A high positive count means the cards left in the shoe are rich in tens and aces. That favours the player, so you raise your bet. When the count is low or negative, you bet the table minimum.

That is the whole idea behind how to count cards playing blackjack. Doing it well is the hard part. You have to keep the count accurately at full dealing speed, convert it for the number of decks left, and still play perfect basic strategy. Even then, the edge is only around 1% in good conditions, and the swings are large.

This guide explains what card counting in blackjack is and why it works. It then walks through the Hi-Lo system with real numbers, shows how the count changes your bets and decisions, and covers the questions most players ask: is it legal, and does it work at online casinos?

Card counting is a way of estimating whether the cards still to be dealt favour you or the dealer. Unlike roulette spins, blackjack hands are not independent. Every card that leaves the shoe changes what can come next until the dealer shuffles.

High cards help the player. A shoe rich in tens and aces produces more blackjacks, which pay 3:2. It also makes your doubles more likely to succeed and makes the dealer bust more often, because the dealer must hit stiff totals like 12–16. Low cards do the opposite: they help the dealer complete weak hands.

The approach was first set out in Edward O. Thorp’s 1962 book Beat the Dealer. Counting does not tell you which card comes next. It only tells you when the odds have shifted slightly in your favour, so you can bet more on those hands and less on the rest.

Hi-Lo is the most widely taught counting system. It is a level-one count, which means every card is worth +1, 0 or −1, so there are no larger numbers to add up.

There are five +1 ranks and five −1 ranks, so a full deck counts to exactly zero. That makes Hi-Lo a balanced count. Balanced systems need one extra step, the true count conversion, in multi-deck games. Unbalanced systems such as Knock-Out (KO) skip that step and are simpler to use, but they usually give up some accuracy in playing decisions.

Step 1: Learn basic strategy first. Counting is built on top of basic strategy. If you are still unsure when to double 11 or split 8s, start with our blackjack rules and basic strategy guide. With good rules, basic strategy brings the house edge down to around 0.5%, though the exact figure depends on the table.

Step 2: Keep the running count. Start at zero after a shuffle. Add or subtract each card’s value as it appears, including other players’ cards and the dealer’s hole card once it is turned over.

Worked example: the first round from a fresh six-deck shoe shows 5, K, 3, 9, A, 6, 2, Q, 4.

• 5 (+1) → +1
• K (−1) → 0
• 3 (+1) → +1
• 9 (0) → +1
• A (−1) → 0
• 6 (+1) → +1
• 2 (+1) → +2
• Q (−1) → +1
• 4 (+1) → +2

The running count is +2. A faster method is to cancel pairs: a high card and a low card seen together add up to zero, so you can skip them.

Step 3: Convert to the true count. A running count of +6 means much more with one deck left than with five. Divide the running count by the number of decks still to be dealt, which you estimate by looking at the discard tray. Most counters round to the nearest half-deck.

• Running count +9, about 3 decks left → true count +3
• Running count +9, about 4.5 decks left → true count +2
• Running count −4, about 2 decks left → true count −2

In a single-deck game you can work from the running count alone.

Step 4: Act on the true count. Use it to decide your bet for the next hand and, once you are more advanced, to change a few playing decisions (covered below).

A common rule of thumb is that each +1 of true count shifts the edge by roughly 0.5% towards the player. Simulations show the real figure varies with the rules, the number of decks and how deep the dealer goes into the shoe, so treat it as a rough guide.

Starting from a house edge of about 0.5%, the player reaches break-even somewhere around a true count of +1 to +2. At +3 the player might have an edge of about 1% (−0.5% + 3 × 0.5%). That small edge is what counting is all about. A £50 bet at a 1% edge is worth an average of only £0.50 per hand, and any single hand can still easily lose.

An example bet ramp

Counters raise their bets in steps as the true count rises. This is called a bet ramp. Here is an illustrative ramp for a six-deck game using a £10 unit:

The gap between your smallest and largest bet is called the spread (1–8 here). Wider spreads earn more but swing harder and draw more attention. In shoe games, a spread of about 1–15 is often described as the practical maximum.

Changing your play

The best-known count-based change is insurance. Basic strategy says never take it, but Hi-Lo players take insurance at a true count of +3 or higher. More advanced players learn a short list of other changes from basic strategy, known as the Illustrious 18 and the Fab 4. These cover most of the value of a full set of count-based rules.

It depends on the type of game:

Most standard RNG games leave you nothing to count. Live tables use real cards, so a count does carry over from hand to hand. In practice, though, many live games shuffle well before the end of the shoe, and that keeps true counts low. Read our live dealer guides to see how these tables are run, and use our guide to choosing an online blackjack table to compare rules such as 3:2 versus 6:5 payouts. The rules matter more for most players than any count.

Keep bonuses separate from counting too. Many casinos count blackjack at a reduced rate towards wagering, or not at all. Check the terms first; our casino bonus terms guide explains how game weighting works.

Counting in your head is not illegal in the UK or under US law. It is simply using your memory. Using a device, an app or an outside helper to track cards is a different matter. That is treated as cheating in many places.

Casinos are private businesses, though, and they can refuse your bets. In land-based casinos, common responses to suspected counters include:

• Shuffling earlier, so less of the shoe is dealt
• Restricting a player to flat bets, or limiting their maximum bet
• Banning players from joining mid-shoe
• Asking the player to stop playing blackjack or to leave
• Switching to continuous shuffling machines

Online, a casino’s terms usually let it limit or close accounts at its discretion. Counting is legal, but there is no guarantee you will be allowed to keep doing it.

• Skipping basic strategy. Playing mistakes cost more than counting brings in. Get basic strategy perfect first.
• Betting on the running count. In a six-deck shoe, a running count of +5 early on is only about +1 true. Always convert.
• Losing the count after a distraction. If you are unsure of the count, go back to minimum bets until the next shuffle.
• Raising bets after losses. Your bet should depend on the count, not on whether you won or lost the last hand. Chasing losses is a different thing and a costly one.
• Underestimating variance. Even with a real edge, a counter can be behind after thousands of hands. A common rule of thumb is a bankroll of about 100 times your largest bet. With the ramp above, that is £8,000.
• Trying it on RNG games. If the deck is reshuffled every hand, there is nothing to count.

1. Deck countdown: deal through a shuffled single deck one card at a time, keeping the count. You should finish on zero. Aim to get through a deck in under 30 seconds with no errors.
2. Pairs: turn over two cards at a time and learn to see their combined value at a glance (K + 5 = 0, 4 + 6 = +2).
3. Deck estimation: stack different numbers of decks and practise judging how many there are, to the nearest half-deck.
4. True count drills: practise dividing quickly, for example +7 with 2.5 decks left is roughly +3.
5. Full simulation: play hands at home with distractions on, combining the count, the conversion, your bet and basic strategy.

Free-play blackjack is useful for drilling basic strategy. Remember, though, that most digital versions reshuffle every hand, so they will not help you practise counting through a shoe. Our blackjack guides cover the rules and table variations in more depth.

• Hi-Lo: 2–6 = +1, 7–9 = 0, 10–A = −1. Keep a running count, then divide by the decks left to get the true count.
• Bet more only when the true count is clearly positive. As a rough guide, each +1 is worth about 0.5% of edge.
• A skilled counter in good conditions has an edge of only about 1%, and the swings are large.
• Counting does not work on standard RNG blackjack and is difficult at most live dealer tables.
• It is legal, but casinos can limit or refuse your play.

Card counting is a test of skill, not a reliable way to make money. Most people who try it make errors that wipe out the small edge. Gambling is for over-18s only. Set a budget you can afford to lose before you play, use the deposit limits and time-outs your casino offers, and stop if gambling stops being fun. If you are worried about your gambling, free, confidential support is available from organisations such as GamCare and BeGambleAware.