Blackjack Deviations Chart: Hi-Lo Index Plays
The plays that change from basic strategy once the count moves, with Hi-Lo true count indexes for dealer hits soft 17 and dealer stands on soft 17, ordered by how much each one is worth.
Updated 2026-10-28 · Hi-Lo · true count = running count ÷ decks remaining
Basic strategy assumes a neutral shoe. When the true count is high, the shoe is rich in tens and aces and some plays flip: you stand more, double more, and take insurance. When it is low, you hit hands you would normally stand on. The tables are ordered by value, so if you learn only the first five you have most of the benefit. Number one, insurance at +3, has its own breakdown with a calculator: when blackjack insurance is worth taking.
Dealer hits soft 17 (H17)
Playing deviations
| # | Hand | Dealer | Index | Basic play | At the index |
|---|---|---|---|---|---|
| 1 | Insurance | A | +3 or higher | No insurance | Take insurance |
| 2 | 16 | 10 | 0 or higher | Surrender | Stand |
| 3 | 15 | 10 | +4 or higher | Hit | Stand |
| 4 | T,T | 5 | +5 or higher | Stand | Split |
| 5 | T,T | 6 | +4 or higher | Stand | Split |
| 6 | 10 | 10 | +4 or higher | Hit | Double |
| 7 | 12 | 3 | +2 or higher | Hit | Stand |
| 8 | 12 | 2 | +3 or higher | Hit | Stand |
| 9 | 9 | 2 | +1 or higher | Hit | Double |
| 10 | 10 | A | +4 or higher | Hit | Double |
| 11 | 9 | 7 | +3 or higher | Hit | Double |
| 12 | 16 | 9 | +5 or higher | Hit | Stand |
| 13 | 13 | 2 | below -1 | Stand | Hit |
| 14 | 12 | 4 | below 0 | Stand | Hit |
| 15 | 12 | 5 | below -2 | Stand | Hit |
| 16 | 12 | 6 | below -1 | Stand | Hit |
| 17 | 13 | 3 | below -2 | Stand | Hit |
Surrender deviations
Only when late surrender is offered. Surrender at the index or higher; below it, play the basic strategy action.
| # | Hand | Dealer | Index | Basic play | At the index |
|---|---|---|---|---|---|
| 1 | 14 | 10 | +3 or higher | Hit | Surrender |
| 2 | 15 | 10 | 0 or higher | Hit | Surrender |
| 3 | 15 | 9 | +2 or higher | Hit | Surrender |
| 4 | 15 | A | +1 or higher | Hit | Surrender |
Dealer stands on soft 17 (S17)
Playing deviations
| # | Hand | Dealer | Index | Basic play | At the index |
|---|---|---|---|---|---|
| 1 | Insurance | A | +3 or higher | No insurance | Take insurance |
| 2 | 16 | 10 | 0 or higher | Surrender | Stand |
| 3 | 15 | 10 | +4 or higher | Hit | Stand |
| 4 | T,T | 5 | +5 or higher | Stand | Split |
| 5 | T,T | 6 | +4 or higher | Stand | Split |
| 6 | 10 | 10 | +4 or higher | Hit | Double |
| 7 | 12 | 3 | +2 or higher | Hit | Stand |
| 8 | 12 | 2 | +3 or higher | Hit | Stand |
| 9 | 11 | A | +1 or higher | Hit | Double |
| 10 | 9 | 2 | +1 or higher | Hit | Double |
| 11 | 10 | A | +4 or higher | Hit | Double |
| 12 | 9 | 7 | +3 or higher | Hit | Double |
| 13 | 16 | 9 | +5 or higher | Hit | Stand |
| 14 | 13 | 2 | below -1 | Stand | Hit |
| 15 | 12 | 4 | below 0 | Stand | Hit |
| 16 | 12 | 5 | below -2 | Stand | Hit |
| 17 | 12 | 6 | below -1 | Stand | Hit |
| 18 | 13 | 3 | below -2 | Stand | Hit |
Surrender deviations
| # | Hand | Dealer | Index | Basic play | At the index |
|---|---|---|---|---|---|
| 1 | 14 | 10 | +3 or higher | Hit | Surrender |
| 2 | 15 | 10 | 0 or higher | Hit | Surrender |
| 3 | 15 | 9 | +2 or higher | Hit | Surrender |
| 4 | 15 | A | +1 or higher | Hit | Surrender |
Learning the indexes
Memorizing the table is the easy part. The failure mode is the trap: a hand that looks like a deviation hand at a count that is one point short. The Deviations mode in Blackjack AI Pro deals index hands at counts on both sides of the index, grades you, and keeps a per-deviation accuracy so you know which ones are solid.
Drill every index play above with trap hands and per-deviation accuracy.
Deviations FAQ
What are blackjack deviations?
Plays that differ from basic strategy because of the count. Basic strategy is right for a neutral shoe. When the Hi-Lo true count is high or low enough, a few hands have a better play: stand instead of hit, double instead of hit, take insurance, or surrender. The true count where the play flips is called the index.
Which deviations matter most?
Insurance at +3 or higher and standing on 16 vs 10 at 0 or higher are worth the most. The tables on this page are ordered by value, so the first five give you most of the benefit.
How do I read the index?
“+3 or higher” means make the deviation play when the true count is +3 or more. “Below 0” means make it only when the true count is negative. Otherwise play basic strategy.
Do the indexes change with H17 and S17?
A few do, and 11 vs ace is not used under H17 because basic strategy already doubles there. This page shows both rule sets from the same engine the app uses.
Where do these indexes come from?
Hi-Lo index numbers come from computer simulation, and the ranking of which plays matter most follows Don Schlesinger’s research in his book Blackjack Attack: Playing the Pros’ Way. The numbers here are the ones the Blackjack AI Pro engine grades against.
The ranking of the most valuable plays follows Don Schlesinger’s research in Blackjack Attack: Playing the Pros’ Way.