In baseball, a fair ball is a batted ball that has not yet become a foul ball, and that...
- settles on fair ground between home and first base, or between home and third base; or
- is on or over fair territory when bounding past first or third base; or
- touches first, second, or third base (which by rule are in fair territory); or
- touches the person of an umpire or player while the ball is on or over fair ground (but a batted ball touching the batter in the batter's box, or bouncing off the ground and immediately hitting the bat is foul even if the contact is over fair territory); or
- passes out of the playing field in flight while over fair ground; or
- touches any part of the foul pole, including an attached screen, while in flight.
It is possible for a ball moving in foul territory to become a fair ball. Batted balls can also be foul balls or foul tips.
Fair territory or fair ground is defined as the area of the playing field between the two foul lines, and includes the foul lines themselves and the foul poles.
A fair ball that is obviously fair is not signaled by the umpires; however, a fair ball that is ruled fair close to the foul lines is signaled by the umpire extending or pointing with his right arm towards fair territory (unless a home run, in which case the home run signal is given). On a fair ball, the batter attempts to reach first base or any subsequent base, runners attempt to advance and fielders try to record outs. A fair ball is considered a live ball until the ball becomes dead by leaving the field or any other method.
Rules in covered facilities
or fixed roof baseball facilities, a batted ball is a fair ball if it:
- strikes the roof, roof support structure, or objects suspended from the roof (e.g., speakers) in fair territory and lands in fair territory, or
- becomes lodged in any of those objects in fair territory and does not fall back to the playing field.
A ball striking or becoming lodged in the roof or suspended object in fair territory beyond the outfield fence is a home run, regardless of where it may land.