The run line is baseball's equivalent of the point spread, providing an alternative to the standard moneyline bet. Like the puck line in hockey, the run line is almost always set at 1.5 runs and is the primary way to bet baseball with a spread rather than a simple win/loss outcome.
Baseball's relatively low-scoring nature (average 9-10 runs per game combined) makes a 1.5-run spread significant. Only a minority of games are decided by 2 or more runs, which is why backing a favourite on the run line at -1.5 often converts their negative moneyline price into a positive price — you are taking a harder proposition for better odds.
Strategic considerations: run line betting depends heavily on starting pitchers and bullpen strength. A dominant ace going against a weak rotation can suggest a larger winning margin. Conversely, in a match between two top pitchers, a 1-0 or 1-0 in extra innings finish is common, making run line -1.5 on the favourite risky.
Alternate run lines are offered by many sportsbooks — -0.5, -2.5, or -3.5 run lines with corresponding odds adjustments. These allow more granular spread betting in baseball, similar to Asian handicap variants in football.
Example
New York Yankees -1.5 (+130) vs Boston Red Sox +1.5 (-150). Yankees are moneyline favourites at -160. You believe the Yankees will dominate with their starting pitcher and bet $100 on Yankees -1.5 at +130. Yankees win 7-3. Margin: 4 runs. The -1.5 run line is covered. Return: $230 ($130 profit).