Short answer: the run line is baseball's version of a point spread, and it's almost always set at 1.5 runs. The favorite is -1.5 (they must win by 2 or more), and the underdog is +1.5 (they cover if they win outright or lose by exactly 1).
Example (no real odds)
Team A -1.5 vs. Team B +1.5:
Example (no real odds)
Team A -1.5 vs. Team B +1.5:
- A wins 5-2 → A covers
- A wins 4-3 → B covers (A won by only 1)
- B wins 3-2 → B covers
- Because the spread is fixed at 1.5, sportsbooks change the price instead of the line.
- A big moneyline favorite often costs less to back on -1.5, because you're taking on the risk of a one-run win.
- An underdog at +1.5 usually costs more than its moneyline price, because you're buying a cushion.
- One-run games are common in baseball, so that half-run matters a lot.
- Home favorites may not bat in the bottom of the 9th when leading, which caps their margin of victory.
- Alternate run lines (like -2.5 or +2.5) and first-five-innings run lines are often available.
- Check house rules on listed pitchers and rain-shortened games. They differ by book.