How to count cards in blackjack, and why it rarely works online

Card counting is a way of tracking which cards have left a blackjack shoe so you know when the cards still to come favour you. It is maths, not magic, and it only works when the game deals from a shoe that is not reshuffled after every hand. That one condition decides whether counting is worth learning for online play in Canada, so this guide explains the method first and then where it does and does not apply. It is an educational explanation, not a way to beat a casino: online and live-dealer blackjack is reshuffled regularly, often after every round, and casinos may restrict or refuse play from people they see as advantage players.

Why the remaining cards matter

In blackjack the cards are not replaced after they are dealt, so every card that leaves the shoe changes the odds for the next one. A shoe rich in tens and aces helps the player for three reasons:

• Blackjacks are more likely, and a player blackjack pays 3:2 while the dealer's blackjack only takes your stake.
• The dealer has no choice. On the Evolution tables documented by theScore Bet, the dealer "must stand on 17 or higher, and draw cards to 16". With many tens left, the dealer busts more often on stiff hands.
• Doubling down works better, because a ten on your 10 or 11 is more likely.

A shoe rich in small cards does the opposite. Counting is simply a fast way to know which kind of shoe you are in.

The Hi-Lo count

Hi-Lo is the most widely taught system because it uses only three values:

Start at zero after a shuffle. For every card you see, yours, the dealer's and the other players', add its value. The total is the running count.

The system is balanced: one deck has 20 cards worth +1 and 20 worth -1, so a full deck counts back to exactly zero. A positive running count means more small cards have gone, which leaves the shoe richer in tens and aces.

Worked example

One round at a six-player table shows these cards: 5, 9, K, 3, 6, A, 2, 10, 4, 7, Q, 5.

1. Small cards (5, 3, 6, 2, 4, 5): six cards, +6.
2. Neutral cards (9, 7): 0.
3. High cards (K, A, 10, Q): four cards, -4.
4. Running count after the round: +2.

From running count to true count

A running count of +2 means a lot with one deck left and very little with seven. The true count corrects for that:

True count = running count / decks remaining

Counters estimate the decks left by looking at the discard tray. In the method, counters raise their bets when the true count is clearly positive and keep them at the table minimum when it is zero or negative. The size of the edge at any count depends on the exact rules, the number of decks and how deep the dealer goes before reshuffling, which is why serious counters work from simulations for one specific game rather than a general rule.

The insurance bet, a clear case

Insurance shows the idea best. You stake half your bet that the dealer's hidden card is a ten-value card, and theScore Bet's rules page says that if the dealer has blackjack "the patron will win twice the insurance bet". So insurance pays 2:1.

• If p is the share of tens among the unseen cards, the bet returns 3p - 1 per unit staked.
• In a full deck, p = 16/52 = 30.8%, so the return is -7.7%. That is the house edge on insurance.
• The bet only breaks even when tens make up exactly one third of the unseen cards, and it pays only above that.

This is why basic strategy says never take insurance, and why counters take it only at high counts.

Online blackjack: where counting stops working

Counting needs memory in the deck. Most online blackjack has none.

With an RNG or infinite deck, each card has the same 1 in 13 chance of being any rank every time. Nothing that came before changes the next card, so the count carries no information. Some live tables in land-based or studio settings still deal from a shoe with a cut card. Read the game's own help page before assuming either way, and note that a deep cut card matters as much as the shoe itself.

The good news is that you do not need counting to play well online. The edge on these games is already small when you follow basic strategy. theScore Bet lists Infinite Blackjack at 99.47% RTP and Blackjack Classic at 99.29%. See the highest RTP casino games in Canada for how those numbers compare with other games, and live dealer casinos in Canada for how live tables are run.

Is card counting legal in Canada?

Counting in your head uses only information every player at the table can see. The Criminal Code's cheating offence, section 209, applies to a person who "with intent to defraud any person, cheats while playing a game". Keeping track of visible cards is not described there.

Devices are a different matter. Nevada, for example, makes it unlawful to use any device that "keeps track of cards played" or analyses the probability of an event in the game (NRS 465.075). Do not use software, apps or hidden aids at any table.

Being legal does not oblige a casino to deal to you. Operators set their own terms. Loto-Québec's online terms, for instance, say it may refuse a bet and set limits on the amounts that can be wagered (clause 7.1.6), and land-based casinos can limit or ban players they see as advantage players.

How the count is practised

The count is usually learned as a mental arithmetic exercise with a deck of cards at home:

1. Count down a single deck: deal one card at a time and keep the running count. You should end on zero.
2. Time yourself. Aim to count a deck in under 30 seconds without errors.
3. Practise pairs: learn to cancel cards that offset, such as a 5 and a king.
4. Add the true count conversion with a known number of decks left.
5. Learn basic strategy perfectly first. Counting on top of strategy errors gains nothing.

Bankroll and limits

Even where a count gives a small edge on paper, results swing widely, and losing streaks can last for hours. Set a deposit limit before you start and treat blackjack, counted or not, as paid entertainment. If you play baccarat as well, note that the same counting logic gives almost no edge there; our online baccarat guide shows the fixed edges on each bet.

Sources

• theScore Bet: Infinite Blackjack rules (Evolution)
• theScore Bet: Blackjack Classic rules (Evolution)
• Shuffle: Original Blackjack game information
• Criminal Code, section 209
• Nevada Revised Statutes, chapter 465
• Loto-Québec: conditions d'utilisation spécifiques