True Count vs Running Count
The single conversion that turns a raw tally into a real, bettable edge.
What is the difference between the running count and the true count?
The running count is the raw total you keep as cards are dealt. The true count converts it into a per-deck figure by dividing the running count by the number of decks remaining. Your real edge - and how much you bet - is based on the true count, not the running count.
Source: Schlesinger - Blackjack Attack, Wong - Professional Blackjack
If there is one step where new counters go wrong, it is this one. Keeping the running count is the easy part; knowing that it is not the number you bet on is what separates a real counter from someone who just watches cards. Here is the difference, and why it matters on every hand.
What is the running count?
The running count is the raw total you keep in your head as cards are dealt. Starting from zero after the shuffle, you add +1 for each low card (2-6), subtract one for each high card (10-A), and ignore the sevens, eights and nines. If the running count is positive, more high cards remain and the shoe is leaning your way. It is the beating heart of counting - but on its own, it is only half the story.
Why the running count alone misleads you
Imagine two tables both showing a running count of +6. At the first, six decks are still to be dealt; at the second, only one deck remains. The second table is far stronger - those six extra high cards are packed into 52 cards instead of spread across 312. The running count is identical, but your edge is completely different. That is the flaw the true count fixes: it measures concentration, not just the raw total.
The true count: running count divided by decks
The true count is simply the running count divided by the number of decks still to be dealt. It expresses your advantage per deck, which is what actually drives your edge. Each +1 of true count is worth roughly half a percent to the player, so at a true count of about +2 you have crossed from underdog to favourite in a standard six-deck game. From there you raise your bets in proportion as the true count climbs.
Estimating the decks remaining
You do not need a perfect count of the cards played - a good estimate is enough. Glance at the discard tray: if it holds about two decks' worth of cards in a six-deck shoe, then roughly four decks remain. Practise estimating in half-deck steps and you will convert quickly enough to keep pace with the dealer. Rounding to the nearest half deck is standard and plenty accurate.
A worked example
Say your running count has climbed to +9. You look at the discard tray and estimate about three decks are left to be dealt. Divide: 9 ÷ 3 = a true count of +3. That is a genuine player advantage of roughly one percent, so this is where you push a bigger bet out. If instead five decks remained, the same +9 would be a true count of under +2 - the same raw number, a much weaker spot. Master this division and the rest of counting falls into place. Next, put it together in how to count cards.