Blackjack Rule Variations and the House Edge
Why the rules matter
Blackjack is not one game. Every table posts its own rules, and each rule moves the house edge up or down. A table can look generous and still be a poor game once you add up the small penalties.
The numbers below are changes in percentage points of house edge, measured against a baseline: 8 decks, dealer stands on soft 17, double on any two cards, double after split, split up to 4 hands, blackjack pays 3:2. That baseline is 0.43%, assuming you play perfect basic strategy.
Rule by rule
| Rule | Effect on house edge | Learn more |
|---|---|---|
| Blackjack pays 6:5 instead of 3:2 | +1.39 | 6:5 vs 3:2 |
| Dealer hits soft 17 | +0.22 | Dealer hits soft 17 |
| No double after split | +0.14 | Double after split |
| Double on 10 and 11 only | +0.18 | Double after split |
| Double on 9 to 11 only | +0.09 | Double after split |
| No resplitting | +0.10 | Double after split |
| Late surrender allowed | -0.07 | Surrender |
| Resplit aces allowed | -0.08 | Double after split |
| Single deck instead of 8 | -0.48 | Number of decks |
| Two decks instead of 8 | -0.19 | Number of decks |
| Six decks instead of 8 | -0.02 | Number of decks |
A positive number helps the house. A negative number helps you.
Rules that affect counters, not the edge
Two features do not change the house edge for a basic strategy player but matter a great deal if you count cards: the continuous shuffling machine and deck penetration. Read these before you waste time practicing card counting for a game that cannot be beaten.
Adding it up
Start at the baseline of 0.43% and apply the changes. The classic 6-deck game where the dealer hits soft 17 comes to about 0.63%: 0.43, minus 0.02 for six decks, plus 0.22 for the soft 17 rule. Add 6:5 blackjack to that and you are at roughly 2.0%, which is where the average player ends up anyway.
The trainer does this arithmetic for you. Change the rules in Settings and the trainer shows the house edge for that game.
Common questions
Which rule matters most?
Blackjack paying 6:5. It costs far more than any other single rule.
Do the rules change basic strategy?
Some do. Soft 17, the number of decks, and surrender all alter specific plays.
Are the numbers exact?
They are approximate. The effects interact, so combining them gives a close estimate, not an exact figure.