Index Deviations

When the count is high enough, the mathematically correct play changes. These are the only deviations worth learning.

Order of operations

  1. Perfect basic strategy first — this is non-negotiable
  2. Learn to count accurately
  3. Then add index deviations — in this order below

Illustrious 18

Accounts for ~80% of index play value. Memorize these before anything else.

1
Any vs A
TC ≥ 3

Take Insurance

2
16 vs 10
TC ≥ 0

Stand (not Sur/Hit)

3
15 vs 10
TC ≥ 4

Stand (not Hit)

4
T,T vs 5
TC ≥ 5

Split 10s

5
T,T vs 6
TC ≥ 4

Split 10s

6
10 vs 10
TC ≥ 4

Double (not Hit)

7
12 vs 3
TC ≥ 2

Stand (not Hit)

8
12 vs 2
TC ≥ 3

Stand (not Hit)

9
11 vs A
TC ≥ 1

Double (not Hit)

10
9 vs 2
TC ≥ 1

Double (not Hit)

11
10 vs A
TC ≥ 4

Double (not Hit)

12
9 vs 7
TC ≥ 3

Double (not Hit)

13
16 vs 9
TC ≥ 5

Stand (not Hit)

14
13 vs 2
TC ≤ -1

Hit (not Stand)

15
12 vs 4
TC ≤ 0

Hit (not Stand)

16
12 vs 5
TC ≤ -2

Hit (not Stand)

17
12 vs 6
TC ≤ -1

Hit (not Stand)

18
13 vs 3
TC ≤ -2

Hit (not Stand)

Fab 4 Surrenders

Surrender deviations — only if the casino offers late surrender.

16 vs 9TC ≥ +2

Surrender (instead of hit)

16 vs 10TC ≥ 0

Surrender (instead of hit/stand)

16 vs ATC ≥ +3

Surrender (instead of hit)

15 vs 10TC ≥ +4

Surrender (instead of hit)

Insurance — The Most Valuable

Take Insurance when TC ≥ +3

Insurance pays 2:1 if dealer has blackjack. At TC +3, you have over 33% of remaining cards being 10-value — meaning insurance is mathematically +EV. This is the single most valuable index play.

Drill Deviations →← Basic Strategy