Basic strategy is the mathematically optimal way to play every possible blackjack hand against every possible dealer upcard. It was first derived by Roger Baldwin et al. in 1956 using hand calculations and later refined by computer simulation. The chart encodes millions of simulated hands to find the single best decision — hit, stand, double, or split — in every scenario.
Why it works: Blackjack is a game of dependent probabilities. The dealer must follow fixed rules (typically hitting until 17 or higher), which means the dealer's upcard is a reliable signal of their likely final total. When the dealer shows a low card (4, 5, or 6), they have a high bust probability — basic strategy exploits this by having you stand on lower totals and double more aggressively. When the dealer shows a strong card (7 through Ace), you take more risk to try to improve your hand.
Rule variations matter: The chart above is optimised for a standard 4-8 deck shoe game where the dealer stands on soft 17 (S17). If your game uses different rules — such as dealer hits soft 17 (H17), restricted doubling, or no double after split — small adjustments apply. The overall house edge difference is modest, but the chart is your baseline.
Card counting: Basic strategy alone does not give the player an edge — it minimises the house edge to roughly 0.5%. Card counters go further by tracking the ratio of high to low cards remaining in the shoe and adjusting their bets and strategy accordingly. Card counting is not illegal, but casinos may ask you to leave. Crypto casinos using provably fair RNG reshuffles effectively eliminate counting as a viable strategy.
Note: This calculator assumes standard multi-deck rules. Always verify the specific rules of the table you are playing. Basic strategy does not guarantee a win on any individual hand — it maximises your expected value over many hands.
