Blackjack Rules & Strategy Guide 2025

Summary: With good rules and perfect basic strategy, blackjack’s house edge can be under ~0.5%. Favor tables that pay 3:2 on a natural, dealer stands on soft 17 (S17), allow double after split (DAS), and offer late surrender (LS). Avoid 6:5 payout games.
Typical house edge: ~0.4–0.6% (3:2, S17, DAS)
Best variant: 1–2 decks, 3:2, S17, DAS, LS
Complexity: Medium–High (chart‑driven)

History

Blackjack evolved from European games like vingt‑et‑un. The modern mathematical approach began in the 1960s with the publication of Beat the Dealer, which popularized basic strategy and card counting. Since then, casinos and players have engaged in a rules‑and‑strategy arms race: more decks and hit‑soft‑17 rules versus better strategy charts, bet‑spreads, and game selection by players.

Rules (Standard)

  • Goal: beat the dealer without busting (exceeding 21).
  • Blackjack (A + 10‑value) beats any non‑blackjack 21.
  • Actions: hit, stand, double (one card), split pairs, surrender (where offered).
  • Dealer: draws to 16 and stands on 17 (some games have H17 – dealer hits soft 17).
  • Insurance: side bet vs dealer blackjack (generally negative EV for players).

Basic Strategy (Quick Keys)

  • Never take insurance / even money in standard rules.
  • Always split A,A and 8,8; never split 5,5 or 10,10.
  • Double 11 vs 2–10; double 10 vs 2–9; double soft A,6 vs 3–6 (S17 tables).
  • Hit hard 12 vs dealer 2–3; stand vs 4–6; otherwise follow chart.
  • Use late surrender on hard 16 vs 9–A (where allowed), except 8,8 is split.

For perfect play, use a printed/basic‑strategy chart matched to your exact rules (decks, S17/H17, DAS, surrender).

Basic Strategy Highlights (Selected)

SituationRecommended ActionNotes
Hard 11 vs 2–10DoubleHit vs Ace in some rule sets; check chart.
Hard 10 vs 2–9DoubleOtherwise Hit.
Soft A,6 vs 3–6 (S17)DoubleOtherwise Hit.
Pairs A,A or 8,8SplitNever split 5,5 or 10,10.
Hard 12 vs 2–3HitStand vs 4–6.

Exact choices depend on decks and table rules (S17/H17, DAS, surrender). Use a chart tailored to your game.

Odds & House Edge (by Rule)

Effects below are Δ in player expected return vs. a base game (8‑deck, 3:2, S17, DAS). Positive = better for player (lower house edge). Negative = worse.

Rule changeEffect on player returnNotes
Blackjack pays 6:5 (vs 3:2)−1.39%Major penalty; avoid these tables.
Dealer hits soft 17 (H17) instead of S17−0.22%Common hidden edge increase.
Late surrender (LS) allowed+0.08%Small but real improvement.
Single deck (vs 8 decks)+0.48%Fewer decks help players (all else equal).
Double deck (vs 8 decks)+0.19%Moderate improvement.
European no‑hole‑card (ENHC)−0.11%Dealer doesn’t peek; doubles/splits risk a dealer blackjack.
DAS not allowed (vs DAS)−0.14%Loss of flexibility after splits hurts.

Example benchmark: under classic Atlantic City rules (6–8 decks, 3:2, S17, DAS), house edge ≈ 0.43% with perfect basic strategy.

Bankroll & Variance

  • Expect swings: even with a 0.5% house edge, short‑term variance dominates.
  • Set session stop‑loss / stop‑win points; avoid chasing losses.
  • Flat bet for simplicity; if you ramp bets, do so modestly and within budget.

Advanced Topics (Overview)

  • Index Deviations: small strategy changes by true count (e.g., stand 16 vs 10 at high counts).
  • Side Counts & Penetration: deeper shoes + accurate counts improve EV but require skill and discipline.
  • Game Selection: picking 3:2, S17, DAS, LS tables typically beats any minor counting edge at bad 6:5 games.

Famous Figures

  • Edward O. Thorp — father of card counting and author of Beat the Dealer.
  • Ken Uston — popularized team play and legal battles on player rights.
  • MIT Blackjack Team — organized advantage play; subject of books/films.
  • Don Schlesinger — risk of ruin, Illustrious 18, bankroll theory.

FAQ

What’s the best quick filter for a good table?

Look for 3:2 payout on the felt, S17, DAS, and surrender; avoid 6:5 tables.

Is insurance ever good?

Generally no for non‑counters; it has negative EV in standard rules.

How much does H17 hurt?

It’s roughly a −0.22% hit to player return compared with S17.