by Norm Wattenberger

Effect of Blackjack Indexes

How do Blackjack indexes affect advantages of counts?

The more indexes that a card counter uses, the higher the advantage. So obviously the advantages at each true count must change. This chart shows the advantages by true count, but only for six decks. The red line is the same as the red line on the chart on the previous page — the advantage using full indexes (over 100.) The green line represents data for the Illustrious 18 and Fab 4 indexes — the most valuable indexes according to Don Schlesinger. The blue line displays the advantages using no indexes — playing Blackjack Basic Strategy. In all cases, the trend is higher advantage at higher counts and the more indexes the higher the advantage. But the effect of using more indexes is different at different counts. At a count of zero it makes little difference as you are playing very close to Basic Strategy. At higher counts, we see that the most important 22 indexes supply most of the gain. In fact at True Counts of +4 and +5 the red and green lines are very close. This is important since TCs of +4 and +5 should be where most of your max bets are placed. At the very low counts, full indexes make a much larger difference. But, you should avoid playing at these counts.


What is the change in advantage from TC to TC?

This chart is like the second chart on the previous page. But here we see the increase in advantage at each count displayed for full, partial and no indexes. Again, a common card counting rule of thumb is that the increase at each count is about .5% for each count. As we can see here this depends on the number of indexes. This is not surprising since the effect of indexes kicks in at different points. The red bars in this chart are the same as the red bars in the chart on the previous page. The green and blue bars show that the gain in advantage per true count is much less with fewer indexes. However, we also see that the gain in advantage is very close between 100+ indexes and 22 indexes at the most important true counts. As we saw on the True Count Frequencies page, the high and low counts rarely occur.


Sim details

  • Six decks, S17, DAS, LS, 4.81/6, Hi-Lo max indexes, trunc, half-deck
  • Two decks, H17, DAS, 1.5/2, Hi-Lo Ill18 indexes, trunc, half-deck
  • Single-deck, H17, 2 players, 4 rounds, Hi-Lo max indexes, trunc, quarter-deck
  • Single-deck, H17, 4 players, 2 rounds, Hi-Lo max indexes, trunc, quarter-deck
  • Ten billion rounds for six and two decks, five billion rounds for single-deck


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