Baseball Infield Fly Rule Explained: When the Batter Is Out

The infield fly rule in baseball can make a batter automatically out even when a high fly ball is not caught. It applies to a fair fly ball that an infielder can catch with ordinary effort when there are runners on first and second (or bases loaded) and fewer than two outs. The rule exists to protect baserunners from an easy, deliberately dropped ball creating a cheap double or triple play.

The authoritative definition comes from MLB’s official Infield Fly glossary, reviewed October 11, 2026.

Infield fly rule: the three conditions

1. Runners must be on first and second, or first, second and third. A runner at third alone, or just a runner at first, does not qualify.
2. There must be fewer than two outs. The rule can apply with zero or one out, not with two.
3. It must be a qualifying fair fly ball that an infielder could catch with ordinary effort. A bunt or line drive is excluded.

All three conditions are essential. If a fly ball is difficult enough to require extraordinary effort, it may not qualify even with the right runners and outs. “Infield fly” does not mean the ball must land strictly inside the dirt infield; the standard concerns what an infielder could catch with ordinary effort.

What happens when the umpire calls “infield fly”?

The batter is out even if the ball drops untouched to the ground as a fair fly ball. The baserunners are not forced to advance because the batter’s out removes the force. They may stay on their bases, or try to advance at their own risk under normal rules.

If the ball is caught, runners who want to advance must observe the ordinary requirements for tagging up after a caught fly ball. If it is not caught, the situation for advancing differs; runners should not assume every dropped ball means an automatic free base.

Why baseball needs this rule

Picture a runner at first, another at second and nobody out. The batter hits a routine pop-up toward the shortstop. Without the infield fly rule, a fielder might let it fall on purpose and then throw to third and second for two quick force outs while the runners remained near their original bases expecting a catch.

The rule removes that incentive: because the batter is already out, the baserunners are no longer forced to leave their bases. The defense cannot routinely exploit the hesitation caused by an easy fly ball.

Infield fly examples

Does the fielder have to catch the ball?

No. The batter’s out is declared based on the qualifying fly ball, not on the completion of a catch. On a fly near a foul line, an umpire may announce “infield fly, if fair,” because a ball that ultimately becomes foul is not the fair fly specified by the rule.

Also remember that normal live-ball considerations still matter. A runner may be put out if they are off base and fail to tag up after a catch, or if they otherwise make an unsuccessful attempt to advance.

Is the rule used in the MLB playoffs?

Yes. This is a standard MLB rule, not a regular-season-only pitch-clock measure. A game in October does not suspend the infield fly rule simply because it is a postseason game.

Readers new to baseball may also want our explanation of innings and outs and our balk-rule primer, which covers a completely different kind of situation.

Infield fly FAQ

Does a runner at first base alone trigger an infield fly?

No. There must be runners on both first and second, or the bases must be loaded.

Is the batter out if the ball falls?

Yes, when the umpire has correctly declared a qualifying fair infield fly.

Do baserunners have to run?

No. They are not forced to advance by the batter after the infield-fly out, but may choose to advance at their own risk.

Photo: James Bond, Wikimedia Commons, CC BY 2.0, unchanged.