Over Under 13 Blackjack Odds
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All over/under bets are settled prior to the play of the blackjack hands. The outcome of over/under bets have no effect on any aspect of the blackjack game. Analysis of the Over/Under Game. Compared to regular blackjack, the over/under game is easy to analyze. By considering all possible two-card totals, it is a straightforward calculation to. The under/over 13 is a side bet in blackjack that a player can make on the first two cards dealt to him, and the bet turns on whether those two cards total under or over 13. Aces always count as one. The dealer automatically wins if the hand totals exactly 13. . Up to three players per Blackjack box may place an Over or Under 13 bet. Winning Over or Under 13 bets are paid even money. If the total of the play- er’s cards equals 13, or is the opposite of the Over or Under 13 bet, the bet loses.
Over Under 13 Blackjack Odds Against
Introduction
Over/Under 13 are a pair of side bets on whether the player's first two cards will total under or over 13. The bets have been around since the 1980's at least and I believe to be among the first blackjack side bets.
Rules
- Both side bets are based on the sum of the player's initial two cards.
- Aces count as one point.
- Both the Over 13 and Under 13 bets lose on a total of 13.
- Wins on both bets pay even money.
- The Majestic casino in Panama City offers a bet on a total of exactly 13, which pays 10 to 1.
Analysis
The following table shows the probability of winning and house edge of the Under 13 bet.
Under 13
| Decks | Probability | House Edge |
|---|---|---|
| 1 | 44.95% | 10.11% |
| 2 | 44.96% | 10.08% |
| 4 | 44.97% | 10.07% |
| 6 | 44.97% | 10.07% |
| 8 | 44.97% | 10.06% |
The following table shows the probability of winning and house edge of the Over 13 bet.
Over 13
| Decks | Probability | House Edge |
|---|---|---|
| 1 | 46.61% | 6.79% |
| 2 | 46.68% | 6.65% |
| 4 | 46.71% | 6.58% |
| 6 | 46.73% | 6.55% |
| 8 | 46.73% | 6.54% |
The following table shows the probability of winning and house edge of the Exactly 13 bet at a win of 10 to 1.
Over Under 13 Blackjack Odds Explained
Exactly 13 — Wins pay 10 to 1
| Decks | Probability | House Edge |
|---|---|---|
| 1 | 8.45% | 7.09% |
| 2 | 8.36% | 7.99% |
| 4 | 8.32% | 8.44% |
| 6 | 8.31% | 8.58% |
| 8 | 8.30% | 8.66% |
Card Counting
Both Under 13 and Over 13 bets are highly vulnerable to card counting (shut up Wiz!). For an thorough treatment of the topic, I recommend Professional Blackjack by Stanford Wong. He covers the topic in chapter 11 of the 1994 edition.