Blackjack Odds & Probability Guide (2025)
Understanding blackjack odds is essential for any serious player. This guide breaks down the mathematics behind the game, including house edge, winning probabilities, and how different rules affect your expected return.
The House Edge in Blackjack
The house edge in blackjack varies based on the rules and number of decks. Here's what you can expect:
| Game Conditions | House Edge |
|---|---|
| Single deck, dealer stands on soft 17, DAS allowed | 0.17% |
| 6-deck, dealer stands on soft 17, DAS allowed | 0.40% |
| 6-deck, dealer hits soft 17, DAS allowed | 0.64% |
| 8-deck, dealer hits soft 17, no DAS | 0.79% |
| Typical Las Vegas Strip game | 0.40-0.60% |
*DAS = Double After Split
Probability of Each Hand Outcome
Based on millions of simulated hands using basic strategy:
| Outcome | Probability |
|---|---|
| Player wins | 42.22% |
| Dealer wins | 49.10% |
| Push (tie) | 8.48% |
| Player blackjack | 4.83% |
| Player busts | 15.96% |
| Dealer busts | 28.36% |
Dealer Bust Rates by Upcard
The dealer's upcard significantly affects their chance of busting:
| Dealer Upcard | Bust Probability |
|---|---|
| 2 | 35.30% |
| 3 | 37.56% |
| 4 | 40.28% |
| 5 | 42.89% |
| 6 | 42.08% |
| 7 | 25.99% |
| 8 | 23.86% |
| 9 | 23.34% |
| 10/Face | 21.43% |
| Ace | 11.65% |
This is why basic strategy tells you to stand on 12-16 against dealer 4-6 — they bust over 40% of the time!
Your Odds of Busting
When you hit, your bust probability depends on your hand total:
| Your Hand | Bust Probability |
|---|---|
| 11 or less | 0% |
| 12 | 31% |
| 13 | 39% |
| 14 | 56% |
| 15 | 58% |
| 16 | 62% |
| 17 | 69% |
| 18 | 77% |
| 19 | 85% |
| 20 | 92% |
| 21 | 100% |
Card Counting and True Count
Card counting changes the odds as the deck composition shifts:
| True Count | Player Edge |
|---|---|
| -5 | -2.5% (house advantage) |
| -2 | -1.0% |
| 0 | -0.5% (basic strategy) |
| +2 | +0.5% |
| +5 | +2.0% |
| +8 | +3.5% |
Note: Card counting is legal but casinos may ask you to leave.
How Rules Affect the House Edge
Each rule variation changes the house edge:
| Rule | Effect on House Edge |
|---|---|
| Single deck vs 8 decks | -0.48% for single |
| Dealer stands on soft 17 | -0.22% |
| Double after split allowed | -0.14% |
| Re-split aces allowed | -0.08% |
| Late surrender allowed | -0.08% |
| 6:5 blackjack payout | +1.39% |
| No hole card (European) | +0.11% |
| Dealer wins ties | +9.00% |
The 6:5 Blackjack Trap
Many casinos now offer 6:5 payouts instead of 3:2. This single change increases the house edge by 1.39%:
- 3:2 payout: $15 profit on $10 blackjack
- 6:5 payout: $12 profit on $10 blackjack
Always look for 3:2 games!
Expected Value of Key Decisions
Here's how much each decision is worth (per $100 bet):
Doubling Down
| Situation | EV if Double | EV if Hit | Gain from Double |
|---|---|---|---|
| 11 vs 6 | +$56.90 | +$29.20 | +$27.70 |
| 10 vs 5 | +$52.10 | +$27.10 | +$25.00 |
| 11 vs dealer Ace | +$17.60 | +$14.90 | +$2.70 |
Splitting Pairs
| Situation | EV if Split | EV Otherwise | Gain from Split |
|---|---|---|---|
| A,A vs 6 | +$61.10 | +$10.00 | +$51.10 |
| 8,8 vs 6 | +$26.40 | -$24.10 | +$50.50 |
| 8,8 vs 10 | -$35.60 | -$53.70 | +$18.10 |
Blackjack Probability FAQs
What Are the Odds of Getting Blackjack?
The probability of being dealt a natural blackjack is 4.83% (about 1 in 21 hands). This comes from:
- Probability of ace first × probability of ten-card second, plus
- Probability of ten-card first × probability of ace second
What Are the Odds of the Dealer Having Blackjack?
When the dealer shows an ace, they have blackjack 30.8% of the time (4/13 cards are tens). When showing a ten-card, they have blackjack 7.7% of the time.
What's the Probability of Winning 5 Hands in a Row?
Roughly (0.42)^5 = 1.3% — about 1 in 77 attempts.
What's the Probability of Losing 10 Hands in a Row?
Roughly (0.49)^10 = 0.08% — about 1 in 1,250 sessions. It will happen!
Using Odds to Make Better Decisions
- Avoid 6:5 games — The math is terrible
- Stand on 12-16 vs 4-6 — Dealer busts 40%+ of the time
- Always split 8s — Even against a 10, it's mathematically correct
- Take advantage of soft hands — Double A-6 vs 3-6
Related Guides
- Master the plays with our Blackjack Strategy chart
- Quick reference: Blackjack Cheat Sheet
- Explore all Blackjack Variations
- Return to the main Blackjack Guide
Frequently Asked Questions
The Bottom Line
Blackjack offers some of the best odds in the casino when played correctly. With basic strategy and favorable rules, the house edge can be as low as 0.17%. Understanding these numbers helps you make smarter decisions at the table and avoid the common traps that increase the house advantage.
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