This card counting calculator turns your running count into the numbers that decide your next bet. Enter the Hi-Lo count and the decks left in the shoe, and it gives the true count, your edge right now, a bet size from a simple ramp and the Kelly bet for your bankroll. It’s free, and it’s built for practice at home, not for a phone under the table.
Card counting calculator: from running count to true count
A running count of +8 means very different things at the start and the end of a shoe. With 6 decks left, those eight extra small cards are spread thin. With 2 decks left, they’re packed in. The true count fixes that by dividing:
True count = running count ÷ decks left
+8 with 4 decks left is +2. +8 with 2 decks left is +4, a much better spot. Judging the decks left is the skill: look at the discard tray, work out how many decks are in it, and take that from the total. Half-deck steps are plenty.
What a true count is worth
With Hi-Lo, each point of true count moves about 0.5% towards you. Start from the house edge off the top, the edge before any cards are seen, and add half a percent per true count. In a game with a 0.5% house edge:
| True count | Your edge |
|---|---|
| 0 | −0.5% |
| +1 | 0.0% |
| +2 | +0.5% |
| +3 | +1.0% |
| +4 | +1.5% |
| +6 | +2.5% |
That’s the reality of counting. Most of the time the count is around zero and you’re the one at a disadvantage. The edge shows up in short spells, and you have to bet more when it does. Get the off-the-top figure for your table from the blackjack house edge calculator: a 6:5 game starts so far behind that counting barely helps.
How much to bet
The calculator uses a common starting ramp: bet the true count minus one, in units, never less than one unit and never more than your spread allows. At +2 that’s 1 unit, at +4 it’s 3 units, at +6 it’s 5. Say your minimum is £10, the running count is +12 and 2 decks are left. The true count is +6, your edge about 2.5%, and the ramp says £50.
Next to it is the Kelly bet: bankroll × edge ÷ 1.33. The 1.33 is the variance of a blackjack hand, which is bigger than an even-money coin flip because of doubles, splits and 3:2 blackjacks. With £5,000 behind you, that +6 count gives a full Kelly bet of about £94. Most counters bet a half or a quarter of Kelly, because the swings at full Kelly are brutal.
If you’re short of bankroll, the calculator will say so. A 1-8 spread with a £10 minimum wants several thousand pounds to ride out a bad run without going broke.
Practise first
None of this helps if the running count is wrong. The card counting trainer deals cards at speed and checks your count and your true count conversion. Pair it with the strategy chart, since counting on top of shaky basic strategy just gives the edge back.
A fair warning: counting is legal, but casinos can refuse your bets or ask you to stop playing blackjack. And the edge is small. At +1% on a £30 average bet, you make 30p a hand on average, with big swings both ways. It’s a grind, not a shortcut.
The bet spread earns most of the edge; the index plays add the rest. The Illustrious 18 lists the ones that matter most, and the blackjack simulator tests a spread over 100,000 hands.
Insurance is the one side bet a counter can beat. The blackjack insurance calculator shows exactly when, from the tens left in the shoe.