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General Sports Betting Articles
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Baseball Handicapping Articles
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Baseball is a game of few runs, so instead of a point spread, sportsbooks offer what's called the run line. The run line is similar to the point spread in that you win if your team covers the run line and lose if they fail to cover the run line. The key difference, however, is that the run line is always 1.5 runs (there are special cases where you might be offered to lay 2.5 runs, but these are ignored in this article).
The Three Run Line Factors
There are three factors that go into creating run line odds that you'll need to take into account before you can confidently bet a given run line. These three factors are: the given team's probability of winning, if the team is on the road or at home, and the total runs scored.
Factor #1: Team's Probability of Winning
The first factor, the team's probability of winning, can be derived using whatever handicapping method you feel comfortable with.
If you don't have a handicapping method you're comfortable with then you can use the market as a guide. To do this you must calculate the no-vigorish price for the game in question. This is covered in more detail in the article calculating the no-vigorish price.
Factor #2: Team's playing at Home versus on the Road
The second factor to calculating run line odds has to do with the difference between playing at home versus on the road. First, however, a look at general run line statistics.
General Run Line Statistics
Before you can calculate run line odds you must be familiar with some general statistics that describe how often teams win by more than 1 run. As a whole, when an MLB team wins they will do so by more than 1 run 72.22% of the time.
This, however, is a very general statistic that can't be used to create odds worth betting, and is the key to this second factor in creating run line odds: the difference between playing at home versus on the road.
Playing at Home Versus on the Road
To get a better idea of what to actually expect in an MLB game as to how it relates to a team covering the run line, you must separate teams that win on the road from those that win at home. There are two important reasons for doing this. First, home teams that are winning after the top of the 9th inning will not bat in the bottom half of the 9th. Second, the game will end if the home team scores the winning run in the bottom half of the 9th or greater inning.
These circumstances cause the home team to have a lesser chance of winning by more than 1 run, and the data supports this. Home teams that win will do so by more than 1 run 68.53% of the time, while away teams that win will do so by more than 1 run 76.51% of the time.
Factor #3: Total Runs Scored
The third factor of calculating MLB run line odds is the total runs scored. Games that have lower run totals are more likely to see a 1 run game than games that have higher run totals. This is a very important factor to creating run line odds, as the run line odds for a game that you expect to score 7 or less runs will be much different from a game in which you expect to see 11 or more runs.
Run Line Relative Frequencies for Various Totals
In a real game you can't possibly know exactly how many runs will be scored until after the game is completed. You can, however, incorporate the expected total runs scored in a given game into your run line odds in one of two ways.
First, you can use your own method of handicapping the total runs to obtain the probabilities of the game going over or under a specific number. If you don't have a handicapping method to do this, you can instead use the market as a guide by calculating the no-vigorish price for the listed total at your favorite sportsbook. For more details on performing these calculations see the article calculating the no-vigorish price.
Once you've obtained a total runs scored number you're comfortable using for calculating run line odds you can use the data in the table below to perform these calculations.
| Win by Exactly 1 Run |
Win by >1 Run |
Total |
Actual Total |
| Home |
Away |
Home |
Away |
| 40.57% | 34.38% | 55.81% | 61.59% | 7 | Less Than or Equal To |
| 23.24% | 15.50% | 74.24% | 82.22% | 7 | Greater Than |
| 34.40% | 28.14% | 62.36% | 68.39% | 8 | Less Than or Equal To |
| 26.23% | 17.56% | 70.98% | 79.89% | 8 | Greater Than |
| 36.61% | 29.55% | 60.44% | 67.27% | 9 | Less Than or Equal To |
| 21.47% | 14.04% | 75.61% | 83.40% | 9 | Greater Than |
| 32.93% | 26.07% | 64.33% | 71.06% | 10 | Less Than or Equal To |
| 25.10% | 16.39% | 71.58% | 80.67% | 10 | Greater Than |
| 34.34% | 26.93% | 63.07% | 70.36% | 11 | Less Than or Equal To |
| 19.55% | 12.33% | 76.96% | 84.70% | 11 | Greater Than |
| 32.13% | 24.68% | 65.40% | 72.79% | 12 | Less Than or Equal To |
| 23.53% | 15.13% | 72.39% | 81.29% | 12 | Greater Than |
| 32.93% | 25.28% | 64.68% | 72.28% | 13 | Less Than or Equal To |
| 17.29% | 10.18% | 78.42% | 86.26% | 13 | Greater Than |
| 31.64% | 23.89% | 66.04% | 73.78% | 14 | Less Than or Equal To |
| 21.26% | 13.15% | 73.62% | 82.37% | 14 | Greater Than |
Note: The data in the table above are the values of the extreme lower end of a 99% confidence interval so that the probabilities are not over estimated. As such, when you calculate run line odds using the data for a specific run line you must use the Win by >1 Run column for calculating -1.5 run line odds, and conversely you must use the Win by Exactly 1 Run column for calculating +1.5 run line odds. Because of this, don't expect the probabilities for the -1.5 and +1.5 run lines for the same game to add up to 100%. This is the expected result, as the extra percentage left over is the margin of error.
Calculating the Odds
With the three run line factors in hand you can now calculate the probability of a team covering -1.5 or +1.5 runs.
Example: Probability of a Home Favorite Covering -1.5 Runs
Suppose a team playing at home is expected to win the game 65% of the time, with the total runs being 8 or less 52% of the time and greater than 8 48% of the time. What would be a fair price for laying -1.5 runs with this team?
First, calculate the probability of the team winning by more than 1 run when the total lands on 8 runs or less:
0.65 x 0.52 x 0.6236 = 0.2057
Next, calculate the probability of the team winning by more than 1 run when the total is greater than 8 runs:
0.65 x 0.48 x 0.7098 = 0.2200
Lastly, add these probabilities together to approximate the total probability of the team winning by more than 1 run:
0.2057 + 0.2200 = 0.4257 = 42.57%
Using a money line converter with this probability the fair odds for this bet is +135 in American odds format.
Example: Probability of a Road Underdog Covering +1.5 Runs
Suppose a team playing on the road is expected to win the game 35% of the time, with the total being 10 or less runs 47% of the time and greater than 10 runs 53% of the time. What would be a fair price for taking +1.5 runs with this team?
First, calculate the probability of the team losing by exactly 1 run when the total lands on 10 runs or less:
(1 - 0.35) x 0.47 x 0.3293 = 0.0987
Next, calculate the probability of the team losing by exactly 1 run when the total is greater than 10 runs:
(1 - 0.35) x 0.53 x 0.2510 = 0.0853
Lastly, add these probabilities together with the underdog's probability of winning to approximate the total probability of the team covering +1.5 runs:
0.0987 + 0.0853 + 0.35 = 0.5340 = 53.40%
Using a money line converter with this probability the fair odds for this bet is -115 in American odds format.
Summary
Using the data and calculations provided in this article you should now be able to calculate run line odds for any Major League Baseball game.
- Ryan J. Parker | Ryan's sports betting blog
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