Free blackjack calculator: get optimal strategy for any hand, view the basic strategy chart, and calculate house edge for your game rules.
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Blackjack Calculator, Probability, Free blackjack calculator: get optimal strategy for any hand, view the basic strategy chart, and calculate house edge for your game rules., blackjack strategy, card counting, 21 game odds, casino probability, calc, compute
Blackjack Calculator
Free blackjack calculator: get optimal strategy for any hand, view the basic strategy chart, and calculate house edge for your game rules.
blackjack strategy, card counting, 21 game odds, casino probability
Probability global
Blackjack Calculator, Probability, Free blackjack calculator: get optimal strategy for any hand, view the basic strategy chart, and calculate house edge for your game rules., blackjack strategy, card counting, 21 game odds, casino probability, calc, compute
Blackjack Calculator
Free blackjack calculator: get optimal strategy for any hand, view the basic strategy chart, and calculate house edge for your game rules.
Select your two cards and the dealer's upcard to see the optimal play
Understanding Blackjack Basic Strategy
What basic strategy is and why every player should use it
Basic strategy is the mathematically optimal way to play every possible blackjack hand. It was first computed in the 1950s by Roger Baldwin and later perfected by Edward Thorp using computer simulations of millions of hands. When you follow basic strategy perfectly, you reduce the house edge to as low as 0.26% — making blackjack one of the best odds in any casino.
Optimal play for every hand
Minimizes house edge
Based on millions of simulations
How basic strategy works
Basic strategy considers two pieces of information: your hand total (and whether it's hard or soft) and the dealer's face-up card. For every combination, mathematics tells us which action — Hit, Stand, Double Down, Split, or Surrender — gives the highest expected value. This calculator uses those derived tables, adjusted for your specific game rules.
Hard Totals, Soft Totals & Pairs
The three categories that determine your optimal play
Hard Totals
10+6 = hard 16, 9+8 = hard 17
A hand without an Ace counting as 11. Hard hands have a real risk of busting when hitting. You stand more often against weak dealer cards (2-6) and hit more against strong ones (7-A).
Soft Totals
A+6 = soft 17, A+4 = soft 15
A hand containing an Ace counted as 11. Soft hands are flexible — the Ace can revert to 1, so you can never bust on one hit. This makes doubling down more attractive against weak dealer cards.
Pairs
8+8, A+A, 5+5
When your two cards have equal value, you can split them into two separate hands. Always split Aces and 8s. Never split 10s or 5s. Other pairs depend on the dealer’s upcard and DAS rules.
How House Edge Works in Blackjack
Understanding the casino's mathematical advantage
The house edge is the percentage of each bet the casino expects to keep over the long run. In blackjack, the house edge depends entirely on the rules of the specific table you're playing at. With optimal basic strategy and favorable rules, the edge can be as low as 0.26%. With poor rules (like 6:5 payouts), it can exceed 2%.
Rule
Impact
Description
Number of decks
-0.48%
Single deck vs 8 decks. Fewer decks favor the player.
Dealer soft 17
-0.22%
S17 (dealer stands) is better for players than H17 (dealer hits).
Blackjack payout
+1.39%
6:5 tables add 1.39% to house edge vs standard 3:2 tables.
Surrender
-0.08%
Late surrender saves ~0.08%. Early surrender (rare) saves ~0.39%.
Double after split
-0.14%
Allowing DAS lets you capitalize on favorable split hands.
The biggest factor is the blackjack payout. Tables paying 6:5 instead of 3:2 add a massive 1.39% to the house edge — roughly six times worse. Always check the payout before sitting down.
Common Blackjack Mistakes to Avoid
Costly errors that increase the house edge
Taking insurance
Insurance is a sucker bet. It pays 2:1 but the odds of the dealer having blackjack are less than 1 in 3. Basic strategy says never take insurance — it costs about 7% on the side bet.
Standing on soft 17
With a soft 17 (A+6), you should always hit or double against dealer 3-6. You can't bust a soft hand on one hit, and 17 loses more often than it wins.
Splitting 10s
A total of 20 is the second-best hand in blackjack. Splitting 10s gives you two weaker hands starting from 10 — always stand on 20.
Not splitting 8s vs a 10
Hard 16 is the worst hand in blackjack. Splitting 8s gives you two chances to improve. Even against a dealer 10, splitting is less costly.
Playing 6:5 tables
The 6:5 payout adds 1.39% to the house edge — roughly six times worse than a standard 3:2 table. Always look for 3:2 tables.
Frequently Asked Questions
Common questions about blackjack strategy, odds, and optimal play
A blackjack calculator uses mathematically derived basic strategy tables to tell you the optimal play (Hit, Stand, Double, Split, or Surrender) for any hand combination. It considers your two cards, the dealer's face-up card, and the specific table rules (number of decks, soft 17 rule, etc.) to compute the expected value of each possible action and recommend the one with the highest mathematical return.
With a hard 16 against a dealer 10, basic strategy says to surrender if allowed, otherwise hit. Standing on 16 loses about 54% of the time because the dealer will make 17 or better most of the time. Hitting gives you a 62% chance of busting, but the times you improve to 17-21 make it the less costly option overall. If late surrender is available, surrendering and losing only half your bet is the best play.
The house edge in blackjack ranges from about 0.26% to over 2%, depending on the table rules. With standard rules (6 decks, dealer stands on soft 17, double after split, late surrender, 3:2 payout) and perfect basic strategy, the edge is approximately 0.26%. The biggest factor affecting house edge is the blackjack payout — 6:5 tables add 1.39% to the house advantage compared to standard 3:2 tables.
Each rule change shifts the house edge: fewer decks favor the player (single deck saves ~0.48%), dealer standing on soft 17 is better by ~0.22%, double after split helps by ~0.14%, late surrender saves ~0.08%, and 3:2 payout is 1.39% better than 6:5. The ideal game is single-deck, S17, DAS allowed, early surrender, and 3:2 payout — but casinos rarely offer all of these together.
No. Basic strategy says never take insurance. Insurance is a side bet that pays 2:1 when the dealer has blackjack, but the true odds of the dealer having a 10-value hole card are approximately 30.8% (not the 33.3% needed to break even). Over time, taking insurance costs you about 7% on the insurance bet. The only exception is for card counters who know the deck is rich in 10-value cards.
A soft 17 is a hand totaling 17 that contains an Ace counted as 11 — for example, Ace + 6. It's called "soft" because the Ace can change from 11 to 1 if needed, preventing a bust. The rule "dealer stands on soft 17" (S17) means the dealer keeps this hand. "Dealer hits soft 17" (H17) means the dealer takes another card, which slightly favors the house because the dealer gets another chance to improve without risk of busting.
Always split Aces and 8s regardless of the dealer's card. Never split 10s (20 is too strong) or 5s (play as hard 10 and double). For other pairs: split 2s, 3s, 6s, and 7s against dealer 2-7; split 4s against dealer 5-6 only if DAS is allowed; split 9s against everything except 7, 10, and Ace. These rules maximize your combined expected value across both split hands.
Expected value (EV) is the average amount you expect to win or lose per dollar wagered over the long run. An EV of +0.10 means you gain 10 cents per dollar bet on average. In the calculator, EV is shown for each action — the action with the highest (least negative) EV is the optimal play. For example, standing on hard 12 vs dealer 4 might have an EV of -0.21, while hitting has an EV of -0.25, making standing the better choice despite both being negative.
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