MLB playoff series odds price a whole round, not a game, so a team that wins 55% of its individual games against an opponent is roughly a 57% favorite over three games, 59% over five and 61% over seven. The edge compounds as the series gets longer, and the series price should move with it. Baseball is where that math matters most, because single baseball games sit closer to a coin flip than games in most sports, and the postseason runs on three different series lengths.
Three series lengths in one postseason
Twelve teams make the MLB playoffs, six from each league: three division winners and three wild cards. The two best division winners in each league skip the first round. Everyone else plays a different length of series depending on the round.
- Wild Card Series, best of three. All three games are played in the higher seed's park.
- Division Series, best of five. A 2-2-1 pattern, so the higher seed hosts Games 1, 2 and 5.
- League Championship Series and World Series, best of seven. A 2-3-2 pattern, so the team with home field hosts Games 1, 2, 6 and 7.
Each round gets its own series price, and the same two teams would deserve a different number in each one. The broad walkthrough of the bracket, the rounds and the bet types is in our guide to betting on the MLB playoffs. This post is only about the price.
How a per-game edge compounds
A series price is the chance of winning enough games before the other team does. Give a team a fixed chance of winning each game, run every possible path through the series, and add up the paths that end with that team on top. Two numbers are enough to see the pattern: a 55% game favorite, which is a fair single-game moneyline of about -122, and a 58% favorite at about -138.
| Per game | Best of 3 | Best of 5 | Best of 7 |
|---|---|---|---|
| 55% (-122) | 57.5% (-135) | 59.3% (-146) | 60.8% (-155) |
| 58% (-138) | 61.9% (-162) | 64.7% (-184) | 67.1% (-204) |
The prices in brackets are fair odds with no margin on top. Two things stand out. First, a short series barely rewards the better team: the 55% club gains only 2.5 points of win probability in a best of three, which is why the Wild Card round produces so many upsets. Second, the gain grows with the size of the edge. The 58% team picks up about nine points over seven games while the 55% team picks up under six. A series price that treats every favorite the same way across rounds is wrong somewhere.
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Worked example: pricing a best-of-seven
Take a League Championship Series where you make the favorite a 55% winner in every game. The fair price on the series is -155. Now ask a narrower question: how does the series end? There are eight possible results, four for each team, and each has its own probability.
Eight results, fair odds with no margin. The four favorite rows add up to the 60.8% series price (-155), and the single likeliest result is 4-2, not a sweep.
A sweep is the least likely way for the favorite to win. It needs four straight wins, and 0.55 to the fourth power is only 9.2%. Longer results are more likely because there are more orders the games can fall in: a 4-2 result can happen ten different ways, a 4-0 only one. That is also why the underdog's likeliest win comes in seven games, at 13.6%, and why the series goes the full seven 30.3% of the time.
To check a posted correct-score price against your own number, turn it into a percentage with the implied probability calculator. If the favorite in 6 is posted at +400, that implies 20.0%. Your fair number is 18.5%, so at your edge the bet loses money. At +500 it implies 16.7% and becomes a bet.
Where series prices go wrong
Round length gets ignored. A favorite's price should lengthen from the Wild Card round to the Division Series to the LCS. If a comparable matchup carries the same number in a best of three and a best of seven, one of the two is off.
Correct-score markets carry more margin. Eight outcomes means eight places to shade a price, and the posted numbers across all eight usually add up to well over 100%. Convert every one before you bet any of them.
The per-game edge is not fixed. The math above assumes the same 55% every game. In reality the rotation matters: a team whose ace can start Games 1 and 5 of a best of five has a different edge in those games than in Game 3. Price each game on its starter, then build the series from those numbers. The regular-season side of the same market, division odds and wild card futures, is covered in how to bet the MLB playoff race, and the final round on its own is in our World Series betting guide. For a free-to-play way to call the whole bracket, see the MLB playoff bracket on BettorEdge. Live games and prices sit on the MLB hub.
MLB playoff series odds FAQ
How do MLB playoff series odds work?
MLB playoff series odds price the chance that a team wins the whole round, which compounds its single-game edge over three, five or seven games, so a 55% game favorite is a fair -155 over a best of seven. The price only settles when one team reaches the needed number of wins, and extra innings count like any other game. A longer series always gives the better team a larger share of the outcomes.
What is a correct series score bet?
A correct series score bet is a wager on the exact final result of a playoff series, such as a team winning 4-2, and it pays far more than the series price because it splits one outcome into four. In a best of seven with a 55% game favorite, the fair odds run from +440 on the favorite in six to +2339 on an underdog sweep. These markets usually carry more margin than the series winner market.
Why is a best of three series more likely to produce an upset?
A best of three is more likely to produce an upset because two wins is too short a run for a better team's edge to add up, so a 55% game favorite wins the series only 57.5% of the time. Stretch the same matchup to a best of seven and the favorite wins 60.8%. That is why MLB's Wild Card Series is the most volatile round of the postseason.
Every series price is a compounded number, and any margin laid on top of it compounds with it. On BettorEdge community odds you set your own series or correct-score price and match it against another real bettor, with no house margin built in. Open BettorEdge and get this price for real, peer-to-peer.
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