Blackjack card counting explained
Card counting tracks which cards have been played to spot shoes rich in 10s and aces. It is legal, but casinos can limit or bar players who do it.
Reviewed Oct 14, 2026
Answer first
90s| Cards | Hi-Lo value | Why |
|---|---|---|
| 2, 3, 4, 5, 6 | +1 | Low cards gone → shoe richer in 10s and aces |
| 7, 8, 9 | 0 | Neutral |
| 10, J, Q, K, A | −1 | High cards gone → shoe worse for the player |
Key numbers
Counting in four numbers
In short
Key takeaways
- Counting does not predict the next card. It tells you when the remaining cards favor you.
- Convert the running count to a true count by dividing by the decks left.
- Bet more when the true count is high and the minimum when it is low.
- Casinos may shuffle early, limit your bets or ask you to leave.
On the felt
Running count after one round
Low cards (+1 each)
+4
High cards (−1 each)
−2
Neutral (0)
0
Running count +2. With 4 decks left, the true count is +0.5.
True count and player edge (6 decks, good rules)
| True count | Approx. player edge |
|---|---|
| −1 | −1.0% |
| 0 | −0.5% |
| +1 | 0% |
| +2 | +0.5% |
| +3 | +1.0% |
| +4 | +1.5% |
Rule of thumb: each true count point is worth about 0.5%.
Playbook · Beginner
Count a shoe
Tip 01
Start at zero
After a new shuffle.
Tip 02
Add and subtract
+1 for 2–6, −1 for 10–A, as cards are shown.
Tip 03
Estimate decks left
Look at the discard tray.
Tip 04
Find the true count
Running count ÷ decks remaining.
Tip 05
Size your bet
Minimum at true +1 or less; raise as it climbs.
Why it works
A shoe rich in 10s and aces gives more blackjacks, which pay 3 to 2 to you but even money to the dealer. Doubles on 10 and 11 also succeed more often.
The dealer must hit stiff hands by rule, so a 10-rich shoe busts the dealer more often.
The gain is small and needs many hands. Swings are large, so counters keep a big bankroll in betting units.
Floor rules
Terms
Know before you sit
- Running count
- The total of card values seen since the shuffle.
- True count
- Running count divided by decks left.
- Penetration
- How far into the shoe the dealer deals before shuffling.
- Back-off
- A casino asking a player to stop playing blackjack.
- Wonging
- Joining a table only when the count is good.
Playbook · Beginner
Practice drills
Tip 01
Single deck
Count down a shuffled deck; you should end at zero.
Tip 02
Pairs of cards
Flip two at a time and cancel high-low pairs at a glance.
Tip 03
True count
Practice dividing by half-deck estimates.
Tip 04
Play with distraction
Count while talking or with TV on.
Keep reading
Related pages
Go play
Where to play in Las Vegas
Tap a resort — each row opens that casino’s White Gambling page (hours, game mix, floor facts). Venues with this game in official counts, sorted high to low.
Open a casino page
Real listings · not adsAfter the 90 seconds
Questions before and after you play
A 90-second guide cannot cover every table moment. Tap a group, then a question — answers are short paragraphs, not one-liners.
01Counting
Is card counting illegal?
No. Counting cards in your head is legal in the US. Using a device to count is illegal in Nevada and many other states. Casinos can still ask a counter to stop playing blackjack.
How much can a card counter win?
A typical counter has an edge of about 0.5–1.5% on total money bet. At $25 average bets and 100 hands an hour, that is roughly $12–$37 an hour on average, with large swings.
What is the Hi-Lo count?
A simple counting system: +1 for 2 through 6, 0 for 7 through 9, and −1 for 10s and aces. It is the most widely taught system.
Does counting work with a shuffling machine?
Not with a continuous shuffling machine, which returns cards to the deck after each round. Automatic shufflers that shuffle between shoes still allow counting.
Do I need basic strategy before counting?
Yes. Most of the counter’s edge assumes perfect basic strategy. Without it, the count only reduces the loss.
Can casinos ban card counters?
In most states, yes. New Jersey casinos cannot bar counters because of a 1982 court ruling, but they can use countermeasures such as frequent shuffles.
02Practice
How do I practice counting?
Count down a single deck, aiming to end at zero, until you can do it in under 30 seconds. Then practice with distractions and with true count conversions.
03More questions
What is penetration?
How far into the shoe the dealer deals before shuffling. Deeper penetration, such as 5 of 6 decks, makes counting more effective.
Can you count cards online?
Not in most online blackjack, which shuffles after every hand. Some live-dealer games deal from a shoe, but cut cards are usually placed early.
What is a bet spread?
The ratio between your smallest and largest bets. A 1-to-8 spread means betting $10 at low counts and $80 at high counts.
Is the MIT team story real?
Yes, MIT students ran organized team play in the 1990s, using counting and signals. Their story inspired books and films, which added drama but were based on real methods.
Sources
- Wizard of Odds — Card counting Not from a registry (Reference source, not an official registry)The gaming industry’s standard reference for casino-game math, by actuary Michael Shackleford. Not an official registry; our calculators compute these numbers independently. · accessed Oct 14, 2026Hi-Lo count and edge
- Nevada Gaming Control Board · accessed Oct 14, 2026Approved games and gaming revenue reports
- National Council on Problem Gambling — Help and resources Not from a registry (Reference source, not an official registry) · accessed Oct 14, 2026Free, confidential help: call or text 1-800-GAMBLER
- American Gaming Association — Research Not from a registry (Reference source, not an official registry) · accessed Oct 14, 2026US casino industry data