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If you want to become a sharp and beat the house, you must understand the underlying mechanics of how to bet on run lines in baseball.  Analyzing the run line can be complex at times, but it can turn into a highly profitable bet for anyone who understands how it works and is willing to study the logistics behind run lines.

Once you’re up to speed on the run line and armed with the necessary knowledge, you’ll have the ability to begin using your smarts to pick the winning numbers.

The Run Line Presents an Additional Betting Option

There are other ways to bet on baseball besides the moneyline, and the run line is one more option. This is very similar to betting the point spread in football. In general, the run line is either -1.5 runs if you are betting on the favorite and +1.5 if you are betting on the underdog.

If we bet the favorite on the run line, we need them to win by at least two runs to win our bet. Conversely, if we bet on the underdog at +1.5, we win our bet if they either win the game outright or lose by only one run.

MLB Games Are Closer in Score Than You Might Think

Understanding the importance of one run is the first thing we need to comprehend, and the numbers may surprise some people. Roughly 28% of all MLB games are decided by one run. That does not mean that the favorite won by one run and/or the underdog lost by a run. It simply means that all games were decided by one run.

Roughly 28% of all MLB games are decided by one run.

The chart below shows the four possible outcomes we’re concerned with in run line betting and sets out the number of games that end with that outcome (based on a sample size of tens of thousands of games). There will be short-term variations within seasons, but this is a great reference point and should hold true over the long-term.

Result  Home Favorite Road Favorite
Win by two or more 39% 44%
Win by exactly one 18% 12%
Lose by exactly one 11% 16%
Lose by two or more 32% 28%

The above table shows that the favorite loses the game outright 43% of the time at home and 44% of the time on the road. When you add in one-run wins for the favorite, which amounts to a loss on the run line, then the favorite is a losing bet 61% of the time at home and 56% of the time on the road.

Does that mean you should always take the underdog? Not so fast. As you’ll see in the next section, -1.5 favorites can still have value.

The Price You Pay: Taking

We already know that the run line in baseball is analogous to the spread in football, in that the favorite has to win by a certain number of runs/points in order to be a winner for bettors.

However, there’s a crucial difference between spread betting and run line betting, and that’s the return on your bet. Sportsbooks are well aware that underdogs cover the run line a lot more than favorites. For that reason, you will (almost always) have to bet more on the underdog in order to win the same amount of money.

As the next table below demonstrates, the payout on run line/spread bets in baseball varies greatly from game to game. Why? Because the value of that single run varies greatly, depending on which teams are playing and which pitchers are starting.

The most important factor in determining the value of a run in a single game is assessing its correlation to the projected total for that game (i.e. the combined number of runs scored by the teams; refer back to the Betting Primer if you forget what baseball totals are.

That sounds complicated, but it’s actually quite simple. If a game has a projected total of 7 runs, then 1.5 runs account for 21.4% of the expected total. Consequently, sportsbooks will make you pay a lot for that run.

If a game has a total of 10 runs, 1.5 runs accounts for only 15% of the expected runs, and you won’t have to pay as much to get the advantage of those 1.5 runs.

The other big factor in determining the payout for the run line underdog is the comparative strength of the teams playing, which you can see by looking at the money line for the game. If a run line underdog is also a big money line underdog, it won’t cost as much to bet on them at +1.5.

The Run Line in Action

In this chart, you can see that Chicago vs Cincinnati has a projected total of 11 runs and that Cincinnati is a big +175 underdog on the money line (ML). For those reasons, taking the Reds +1.5 is only -115 (meaning you need to bet $115 on Cincinnati to win $100). With 11 runs expected, the importance of a single run is less likely to matter. That doesn’t mean it won’t matter. It’s just less likely to matter given that the game is expected to be relatively high-scoring. And with Chicago heavily favored to win the game outright, the potential for a one-run win (versus a two-run win, or more) goes down.

The game between Milwaukee and San Diego lies at the other end of the spectrum. It has a projected total of only 7.5 runs, and Milwaukee is only a small +118 underdog on the money line.

Therefore, Milwaukee +1.5 runs has a payout of -195, meaning the sports book will make you risk $195 just to win $100. In essence, by giving Milwaukee those 1.5 runs, you have taken a short underdog (+118) and turned them into a large favorite (-195).

The Price You Pay on the Run Line: Giving

If you wanted to get a bigger payout from the San Diego/Milwaukee run line, you could take San Diego -1.5 runs at +166. (Remember, since that’s a positive number, it means you only have to bet $100 in order to win $166.) But the chances of San Diego winning by two runs or more is not great.

If you refer back to our percentages above, you’ll recall that home favorites only win by two runs or more 39% of the time. And that’s for all games, including ones where the home team is a big favorite on the money line. In this case, San Diego is only a tepid home favorite on the money line.

The Cubs, on the other hand, are a big money line favorite and are expected to play a high-scoring game. As a result, Chicago -1.5 has a lower payout of -105. (You must bet $105 to win $100.)

Road favorites win by two runs (or more) at a higher rate than home teams.

If you follow sports at all, you’ve probably heard the term “home-field advantage” many a time. So it might come as a shock to see that road favorites win by two runs (or more) at a higher rate than home teams. But there’s a simple explanation for this.

Remember that home teams in baseball do not bat in the ninth inning if they are ahead. If they are up by any margin after 8.5 innings, the game is over. Removing that ninth at-bat takes away a whopping 11% of the home team’s opportunities to score.

Advanced Considerations in Run Line Betting

We have looked at the basic pros and cons for both sides of the run line. But know that there are many more variables that come into play, and sportsbooks tend to be on top of these and factor them into the line.
Some examples are:

  • Which pitchers are starting that day (the Dodgers will almost always be ML favorites when Clayton Kershaw is on the mound, and the total will usually be lower)
  • Recent bullpen activity for each team (tired and overworked bullpens will lead to higher totals)
  • Key injuries to offensive stars (taking Mike Trout out of the lineup will impact how big a favorite/underdog the Angels are and the expected total to some extent)

Games can also be canceled for a variety of reasons, such as rain-outs or lightning storms. If a game does not go 8.5 innings, run line bets are nullified. If a game is called due to weather in the 6th inning, the bet is canceled, even if your team is winning by ten runs. It does not matter that MLB calls the game official and declares a winner.

There Are Always More Options on the Run Line

Many sportsbooks offer “alternative” run lines, as shown in the chart below. In this instance, the alternative run line is allowing you to take the underdog to win the game by two or more runs.

In the case of rotation number 3910, the San Francisco Giants, they are prohibitive underdogs (+140) on the money line against the Dodgers. So the chances of them winning by two runs or more are not great. But, if they do, they will net their backers a pretty penny, since the payout on San Francisco -1.5 is +300.

That +300 number equates to an expected win-rate of only 25%, and we know from the chart above that road favorites (in this case, the Dodgers) lose by two or more runs 28% of the time, making a bet on the Giants worthy of consideration.

Or, if you think the Dodgers might be in for a close game, you could get the favorite +1.5 runs. Of course, you have to pay -400 which is something most bettors – beginner or otherwise – will only want to consider in a parlay.

If you are not willing to lay -150 on the money line (which requires the Dodgers to win outright at a 60% rate), then it doesn’t make sense mathematically to take -400 (which requires the Dodgers to win or lose by one run at an 80% rate). However, those options are out there.

In the chart above, you would be better off taking the White Sox at -1.5 (+250) for no other reason than the fact that you are assured as a road team of getting 27 outs.

One of the most affordable ways to play a large money line favorite is to split the bet evenly between the money line and the run line.

One of the most affordable ways to play a large money line favorite, assuming you don’t want to lay -200 (or more), is to split the bet evenly between the money line and the run line. Of course, if the team wins by one, you lose half of the wager, but it does mitigate possible damage.

The other option that some books offer is a -1 run line, which is priced exactly the same as splitting the bet between the run line and the money line. Then, if your -200 team does win by one run, you push the wager.

Get Started Betting on Baseball Today!

To summarize, there is no magic bullet or perfect mathematical scenario to winning on the run line. There are things you can do that will minimize the risk, and that is how recreational bettors usually look at things. They might decrease your ROI, but any positive ROI in sports betting is a good thing.

Curious to learn more about the ins and out of betting on baseball, or just betting on sports in general? Visit our comprehensive guide on how to bet on sports, or take a glance at our 101 guide to betting on baseball.