New counters often get excited when the running count climbs. Plus 4, plus 6, plus 8 - the numbers feel powerful. But the running count alone does not tell you whether the remaining deck is actually favorable. For that, you need the true count.
The dilution problem
Imagine a running count of +6. If there are two decks remaining in the shoe, that +6 is concentrated across relatively few cards. The density of high cards is meaningfully shifted in your favor. But if there are six decks remaining, those same +6 extra high cards are spread across six decks. The density shift is barely noticeable.
The conversion
True count = running count / decks remaining. A running count of +6 with 2 decks remaining gives a true count of +3. The same +6 with 6 decks remaining gives a true count of +1. The first scenario is strong enough to raise your bet significantly. The second is barely worth adjusting.
Estimating decks remaining
You do not need to be exact. Look at the discard tray. If the shoe started with six decks and the discard tray looks like it holds about two decks, there are roughly four decks remaining. Practice this estimation at home by stacking cards and eyeballing deck sizes until you can estimate within half a deck.
When to act on the true count
Most counting systems suggest increasing your bet when the true count reaches +2 or higher. Below that, the advantage is too small to overcome the variance. At +2, the player edge starts to become real. At +3 or above, skilled counters may increase bets substantially. The true count is the trigger. The running count is just raw data.
