Blackjack · Free tool
Blackjack Calculator: The Best Move for Any Hand and Rule Set
Quick answer
Enter your two cards, the dealer's upcard and the table rules, and this blackjack calculator shows the basic-strategy move: hit, stand, double or split. Basic strategy is the mathematically best play for every hand. Following it on a 6-deck, dealer-stands-on-soft-17 game cut the house edge to about 0.47% in our 10-million-hand simulation.
| What it tells you | Best move: hit, stand, double or split |
|---|---|
| Strategy source | 4–8 deck basic strategy (Wizard of Odds charts) |
| House edge, 6 decks S17 DAS, 3:2 | About 0.47% (our 10M-hand simulation) |
| Rules covered | Dealer stands or hits soft 17; double after split allowed or not |
This blackjack calculator tells you the mathematically best move for any starting hand. Choose your two cards, the dealer's upcard and the table rules. It returns the basic-strategy play and the house edge for that rule set from our own 10-million-hand simulation.
The default shows one of the most common tough spots: hard 16 against a dealer 10. The answer is to hit.
How the blackjack calculator works
The calculator looks up your hand in the basic-strategy chart for the rules you chose. Basic strategy is the set of plays that loses the least over the long run for every combination of player hand and dealer upcard. Our charts follow the published 4–8 deck strategy, and they're the same charts our simulator played.
It sorts your hand into one of three types first, because they're played differently:
- Pairs (two cards of the same value): split or play as a total.
- Soft hands (an ace counted as 11): you can't bust with one more card, so you can play them more aggressively.
- Hard hands (everything else).
Then it reads the move for that hand and the dealer's upcard. "Double" means double your bet and take exactly one more card. Some doubles say what to do if doubling isn't allowed, which matters after a hit or on tables that restrict doubling.
House edge by rule set: our 10-million-hand simulation
We simulated 10 million hands of perfect basic strategy for each rule set and scored every hand at both 3:2 and 6:5 blackjack payouts:
| Rules | House edge at 3:2 | House edge at 6:5 | Standard error |
|---|---|---|---|
| 6 decks, S17, DAS | 0.47% | 1.83% | ±0.036 |
| 6 decks, S17, no DAS | 0.53% | 1.89% | ±0.036 |
| 6 decks, H17, DAS | 0.65% | 2.01% | ±0.036 |
| 6 decks, H17, no DAS | 0.78% | 2.13% | ±0.036 |
Paying 6:5 instead of 3:2 cost the player 1.36 percentage points in our run, close to the 1.39 points the Wizard of Odds publishes. That's a bigger penalty than any other common rule change, which is why our 6 to 5 blackjack guide recommends avoiding those tables.
Our simulator uses simplified rules (one split per hand, no surrender, split aces get one card), so exact figures can differ slightly from a full calculator. The Wizard of Odds house edge calculator covers every rule combination.
Worked examples
| Your hand | Dealer upcard | Best move (S17, DAS) |
|---|---|---|
| Hard 12 (10, 2) | 3 | Hit |
| Hard 12 (10, 2) | 4 | Stand |
| Hard 11 (6, 5) | A | Hit |
| Soft 18 (A, 7) | 9 | Hit |
| Soft 18 (A, 7) | 5 | Double (else stand) |
| Pair of 8s | 10 | Split |
| Pair of 9s | 7 | Stand |
| Pair of 5s | 6 | Double |
A pair of 5s is played as a hard 10, so you double against a 6 rather than splitting. Nines are split against a 7 but not against a 10 or an ace, because 18 already beats a dealer's likely 17.
Using it with real tables
- Check the rules before you sit down. The soft-17 rule, double-after-split and the blackjack payout are usually printed on the table or in the game's help screen.
- Avoid 6:5 games. No strategy recovers that 1.36-point cost.
- The calculator can't beat the edge. It shows the least-bad play, not a winning one.
For a printable version of the full chart, see our blackjack strategy card. To understand when to split, read what split means in blackjack. And if you want a game with a fixed, published edge and verifiable rounds, compare crypto dice at a 1% edge.
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Frequently asked questions
Does a blackjack calculator guarantee wins?
No. Basic strategy gives the lowest possible house edge for a rule set, but the edge is still there. In our simulation of a 6-deck game where the dealer stands on soft 17, perfect basic strategy still lost about 0.47% of the initial bet per hand on average.
What should I do with 16 against a dealer 10?
Hit, if surrender isn't offered. Hard 16 against a 10 is the worst common hand in blackjack: both hitting and standing lose more often than they win. Hitting loses slightly less over the long run. Where late surrender is allowed, basic strategy surrenders instead.
What changes when the dealer hits soft 17?
The house edge goes up (by about 0.18 points in our simulation, 0.22 per the Wizard of Odds), and three plays change: double 11 against an ace, double soft 18 (A,7) against a 2, and double soft 19 (A,8) against a 6.
Is this calculator allowed at online casinos?
Using a strategy chart is generally treated differently from cheating devices, but rules vary by operator and jurisdiction. Check the terms of the site you play on. Many players simply memorise the chart, which our strategy card page helps with.
Sources
- 4-Deck to 8-Deck Blackjack Strategy — Wizard of Odds. Basic strategy charts for 4-8 decks, H17 and S17
- Blackjack Rule Variations — Wizard of Odds. 6:5 -1.39%; H17 -0.22%; no DAS -0.14%; single deck +0.48%; double deck +0.19%; 4 decks +0.06%; 6 decks +0.02% (vs 8-deck S17 baseline); late surrender +0.07%
- Blackjack Basics — Wizard of Odds. Card values; split; double; push; blackjack pays 3 to 2