Blackjack payout: 3:2 vs 6:5 6:5 ≈ +1.4%

The single most important rule. A natural blackjack should pay 3:2 — a $10 bet wins $15. A 6:5 table pays only $12 on that same blackjack, and 1:1 ("even money") pays just $10. Since you make a blackjack about once every 21 hands, shorting the payout adds roughly 1.4% to the house edge — more than every other rule below combined.

The trap: "single deck" tables are often 6:5. Fewer decks help, but never enough to make up for a 6:5 payout. Always read the felt: if it says 6:5, walk away.

Soft 17: S17 vs H17 H17 ≈ +0.2%

A "soft 17" is an ace plus a six (counts as 7 or 17). Under S17 the dealer stands on it; under H17 the dealer draws another card. Letting the dealer hit soft 17 gives them extra chances to improve, costing you about 0.2%. Prefer tables that say "dealer stands on all 17s."

Double after split (DAS) allowed ≈ −0.14%

After you split a pair, DAS lets you double down on the resulting hands when the new two-card total is strong. It's a free option that only helps you, worth about 0.14% in your favor. No-DAS tables take that option away.

Late surrender available ≈ −0.08%

Surrender lets you fold a bad hand — like hard 16 vs a dealer 10 — and forfeit only half your bet instead of risking the whole thing. "Late" means it's offered after the dealer checks for blackjack. Used correctly on a few specific hands, it's worth roughly 0.07–0.10% in your favor. Rare, but a plus when you find it.

Doubling: any two cards vs 9–11 only restricted ≈ +0.1–0.2%

The best rule lets you double down on any two-card total. Restricting doubles to hard 9–11 (or worse, 10–11 only) removes profitable doubles like soft hands and costs you roughly 0.1–0.2% depending on how tight the limit is. Look for "double on any two cards."

Number of decks fewer ≈ −0.2 to −0.5%

All else equal, fewer decks lower the house edge: single deck is best, then double deck, with 6- and 8-deck shoes the worst. The swing from an 8-deck shoe to single deck is roughly 0.5% in your favor (double deck saves about 0.2%).

The catch: casinos know this, so low-deck games are the ones most likely to pay 6:5. A single-deck 6:5 game is worse than a 6-deck 3:2 game. Deck count only matters once the payout is 3:2.

Splitting & aces: re-split, re-split aces, draw to split aces each ≈ −0.03 to −0.14%

Generous split rules each shave a little off the edge: being allowed to re-split pairs (up to 3–4 hands), to re-split aces (RSA), and to draw more than one card to split aces all help. Drawing to split aces is the biggest of these at about 0.14%; the others are smaller. Most tables give split aces just one card each and no re-split — a table that doesn't restrict them is a bonus.

Continuous shuffle machines (CSMs) more hands/hour

A CSM feeds cards back into the shuffler after every round, so there's no shoe to finish and dealing never pauses. The per-hand edge barely changes, but you play far more hands per hour — often 20% or more — so your expected hourly loss rises with the volume. A hand-shuffled or standard shoe game deals slower and keeps more money in your pocket over time.

Side bets ≈ 5%+ house edge

Bets like "21+3," "Perfect Pairs," and insurance are separate wagers with house edges typically 5% and up — many times worse than the main game. They're designed to look exciting and take your money quickly. Skip them entirely, including insurance, and bet only the base game.