Two numbers, two jobs
Running count
Start at zero after a shuffle. Add +1 for each exposed 2–6, add 0 for 7–9, and subtract 1 for every exposed ten-value card or ace.
True count
Divide the running count by estimated decks remaining. The result describes the imbalance per remaining deck.
True count = running count ÷ estimated decks remaining
Why the conversion matters
A running count of +6 with six decks still in the shoe is approximately +1 per deck. A running count of +6 with only two decks left is approximately +3 per deck. The raw imbalance is identical, but its concentration is not.
Negative numbers work the same way: −4 with four decks remaining is −1; −4 with one deck remaining is −4. This arithmetic does not predict the next card or guarantee any result.
A repeatable conversion process
- Keep the running count until the current exposure sequence is complete.
- Estimate the decks still unseen, not the decks already discarded.
- Divide the running count by that estimate.
- Apply one documented rounding convention consistently.
Different counting materials may truncate, floor, or round true counts differently, especially for negative values. Third Base divides by the exact cards remaining and truncates the displayed result toward zero. When comparing an index source, use the source’s stated convention.
Exact trainer data versus a physical shoe
The trainer knows exactly how many cards remain because it controls the simulated shoe. A person at a table must estimate from the discard tray and shoe. Treat the trainer’s value as an arithmetic check, not as proof that your visual estimate would be equally precise.
Useful drill: hide or ignore the displayed true count, estimate decks remaining, calculate the value yourself, then compare. Separate a counting error from a deck-estimation error.
Common errors
- Dividing by decks already played rather than decks remaining.
- Converting after every card and losing the running count.
- Using an unrealistically precise decimal estimate.
- Changing rounding conventions only when a borderline result feels convenient.
- Treating the true count as a forecast rather than a composition estimate.
Practice sequence
First make card tags automatic with the Hi-Lo guide. Next practise maintaining the running count through complete hands. Then work on deck estimation independently before combining the two skills in the Third Base trainer.