Blackjack Basic Strategy

What Basic Strategy Actually Is

Basic strategy is the mathematically optimal decision for every possible blackjack hand against every possible dealer upcard. It is not a betting system, not a hunch, and not a shortcut to beating the house. It is a complete decision matrix — computed by running every combination of player hand and dealer upcard through probability theory and millions of simulated shoes.

The foundational work was done in the 1950s by four mathematicians — Roger Baldwin, Wilbert Cantey, Herbert Maisel, and James McDermott — who published "The Optimum Strategy in Blackjack" in the Journal of the American Statistical Association. Edward Thorp refined and popularized the strategy in his 1962 book Beat the Dealer, using early IBM computers to simulate millions of hands. The strategy has been verified and re-verified with modern computing. The maths is settled.

Basic strategy does not give you an edge over the casino. It minimizes the house edge to approximately 0.5% — meaning you lose about $5 for every $1,000 wagered, on average. Without it, the typical recreational player faces a house edge of 2-3%. The casino allows strategy charts at the table because 85%+ of players either do not use them or do not use them correctly. The effective house edge from recreational play is far higher than the theoretical minimum.

The 10 Golden Rules

These 10 rules cover approximately 80% of every decision you will face at a blackjack table. Memorize them first. The full chart handles the remaining 20%.

The Full Basic Strategy Chart

Read the chart as follows: find your hand total in the left column, then look across to the dealer's upcard. The cell tells you the optimal action. The chart assumes 4-8 decks, dealer stands on soft 17, and doubling after splitting is allowed — the most common ruleset in both brick-and-mortar and online casinos.

Hard Totals

Soft Totals

Pairs

The Probability Behind the Hardest Decisions

The chart contains several plays that feel wrong. That discomfort is the gap between intuition and arithmetic. Here is the probability behind the five most counterintuitive decisions.

Hit 12 vs Dealer 2 or 3

Your bust probability with a 12 is only 31%. That means 69% of the time you improve or stay alive. Meanwhile, a dealer showing 2 busts only 35% of the time, and a dealer showing 3 busts 37% of the time. Standing gives the dealer too many ways to make 17-21. The small bust risk of hitting is outweighed by the dealer's likely strength.

Hit 16 vs Dealer 10

Standing on hard 16 against a dealer 10 loses approximately 77% of the time. Hitting loses approximately 74%. Neither option is good — but hitting is marginally less bad. The difference of ~3 percentage points is small, which is exactly why this play feels so uncomfortable. Your brain registers both outcomes as "probably losing" and defaults to the passive option. The maths says take the active one.

Double A,7 vs Dealer 3-6

You have soft 18 — which feels strong enough to stand on. But dealer upcards of 3-6 bust 37-42% of the time. By doubling, you win double when the dealer busts, and you have a chance to improve to 19, 20, or 21. Even if your double card weakens you, the dealer's high bust rate makes the extra money profitable in expectation.

Split 8s vs Dealer 10

Two 8s give you 16 — the worst hand in blackjack. By splitting, you create two separate hands each starting from 8, which is a much better foundation. You will likely lose both hands against a dealer 10. But you will lose less total money than playing the 16 straight. The expected loss per dollar wagered is lower with the split.

Never Take Insurance

Insurance is a side bet that the dealer has blackjack when showing an Ace. It pays 2:1. With a 4-deck shoe, the probability of the dealer having a 10 in the hole is approximately 30.8%. For the 2:1 payout to be fair, the probability would need to be 33.3%. The difference gives the casino a house edge of 7.4% on insurance — one of the worst bets on the table. It does not matter what your hand is. Insurance is a separate, mathematically unfavourable bet.