Enter your running count and how many decks are left. The calculator converts it to a true count, estimates your edge for the table rules, and suggests a bet size.
The true count formula
True count = running count ÷ decks remaining
The running count says how many extra high cards are left; the true count says how concentrated they are. A running count of +6 is strong with 1 deck left (+6) and weak with 6 decks left (+1). That is why balanced counts such as Hi-Lo bet off the true count.
Worked true count examples
Running count
Decks left
True count
+6
3
+2
+6
1.5
+4
+10
4
+2.5
−4
2
−2
What the results mean
True count is to one decimal place.
Betting count truncates toward zero (+2.9 becomes +2), the convention the app uses for bets and strategy deviations.
Player edge starts from the house edge for your rules and adds about 0.5% per true count point (0.46–0.51% depending on the system). It is an estimate for practice, not a guarantee.
Suggested bet follows the app's default ramp: 1 unit below +1, then 2, 4, 8 and 12 units at true counts of +1, +2, +3 and +4.
Estimating decks remaining
Glance at the discard tray, judge how many decks have been played, and subtract from the shoe size. Estimating to the nearest half deck is accurate enough for betting.
The true count also tells you when to deviate from basic strategy. See the index plays on the basic strategy chart. To turn a count into a dollar bet for your system and unit, use the bet spread calculator.
Sources
CounterCalculations.kt in the Counting Edge source: house edge by rules and edge per true count
Divide the running count by the number of decks still in the shoe. A running count of +6 with 3 decks left is a true count of +2.
Should I round or truncate the true count?
For betting decisions most counters truncate toward zero, so +2.9 is treated as +2. It is slightly conservative and easy to do at the table. Counting Edge truncates the same way.
How do I estimate how many decks are left?
Look at the discard tray, judge how many decks have been played, and subtract from the total. Estimating to the nearest half deck is accurate enough.
Do KO and ReKO need a true count?
No. KO and ReKO are unbalanced counts that start below zero so the running count can be used directly. Their bet changes happen at a key count instead.
Practice on Android
Let the App Do the Division
Counting Edge tracks the running count as you tap cards, converts it to a true count as the shoe is dealt, and updates your edge and bet live. Free and open source.