The infield fly rule says that when there are runners on first and second (or the bases loaded) with fewer than two outs, and the batter hits a fair fly ball that an infielder can catch with ordinary effort, the umpire can declare the batter automatically out — even before the ball is caught. The rule exists purely to stop defenses from gaming the situation by letting an easy pop-up drop on purpose to turn it into a double or triple play. Once the umpire calls it, the ball stays live, but the batter is out regardless of what happens next.
It sounds complicated the first time you hear it, but the logic behind it is simple, and once it clicks, you’ll never be confused by it again. Let’s walk through it step by step.
What the rule is actually protecting against
Imagine runners on first and second, nobody out. The batter lifts a routine pop-up a few feet behind the shortstop — the kind of ball an infielder catches nine times out of ten without even thinking about it. Without a special rule, a clever defender could let that ball drop untouched, then scoop it up and fire to third, then to second, for an easy double play, because the runners had to stay near their bases in case the ball was caught. The runners are caught in an impossible spot: if they run, they risk being doubled off; if they stay, the defense turns two outs on a ball that should have produced only one.
The infield fly rule closes that loophole. By ruling the batter out the moment the umpire judges the ball catchable with ordinary effort, the rule removes the incentive to drop it. Runners can then advance at their own risk, just like on any other fly ball, without worrying about a sneaky double play.
The conditions that all have to be true
This is where a lot of fans get tripped up, because the rule only applies in a fairly narrow set of circumstances. All of the following have to be true at once:
- Fewer than two outs. With two outs already, there’s no double-play threat, so the rule doesn’t apply.
- Runners on first and second, or the bases loaded. The rule requires a force situation at both second and third — it doesn’t apply with a runner only on first, or only on third.
- A fair fly ball. Line drives and bunts are specifically excluded, even if an infielder could easily catch them. The rule is aimed at ordinary pop-ups, not hard-hit balls or short bunted balls.
- Catchable with ordinary effort. This is a judgment call left to the umpire, not a fixed distance or height. An outfielder can catch an infield fly too — if a shallow pop-up drifts out toward left field but an infielder settles under it easily, it’s still an infield fly.
If any one of those conditions is missing, the play is just a normal fly ball, and the usual rules about tagging up and advancing apply.
Who makes the call
The umpire — usually the one closest to the play, but any umpire can make the call — announces “infield fly, if fair” as soon as the ball’s trajectory makes the situation clear, often while it’s still in the air. That verbal signal is important because it tells runners and the defense that the batter is already out, so nobody needs to guess or react out of panic. If you’re at a game and hear an umpire shout something during a routine pop fly, that’s usually what’s happening.
What happens to the runners
Here’s the part that trips people up most: the ball stays live. The batter is out, but the runners are not forced to stay put the way they would be on a caught fly ball where the defense might try to double someone off. They can advance if they choose to, but they do so at their own risk, exactly as they would on any fly ball — if the ball is caught, they need to tag up before running; if it drops, they can run without tagging, but a good throw can still get them if they’re too aggressive. The rule simply removes the guaranteed double play; it doesn’t guarantee the runners a free base.
What if the ball drops foul, or isn’t caught at all
If the umpire has called infield fly and the ball then rolls foul before being touched, it’s simply a foul ball, and the infield fly call is wiped away — the batter is not out, and the at-bat continues as normal. If the ball is fair and lands untouched, the batter is still out under the infield fly call, but the ball remains live, which is why fielders sometimes let it drop anyway; there’s no penalty for them doing so once the rule has been invoked, since the “trick play” advantage has already been eliminated.
A quick reference table
| Situation | Does infield fly rule apply? |
|---|---|
| Runner on first only, one out, pop fly to shortstop | No — needs runners on first and second, or bases loaded |
| Runners on first and second, two outs, easy pop-up | No — needs fewer than two outs |
| Bases loaded, one out, routine pop-up to third baseman | Yes |
| Runners on first and second, no outs, sharp line drive to second baseman | No — line drives are excluded |
| Runners on first and second, one out, shallow pop-up caught easily by left fielder | Yes, if catchable with ordinary effort |
The rule has been part of the sport for well over a century, dating back to an era when the game looked very different in almost every other way — you can read more about that stretch of baseball history, including the low-scoring, small-ball style of play that shaped so many of the rules still on the books today, in our piece on the dead ball era. Rules like this one are a reminder that a lot of baseball’s structure grew out of real, exploited loopholes rather than abstract fairness — the same is true of how equipment and strategy evolved, which we cover in our look at how the baseball glove has changed over the last century and a half.
Why this rule matters beyond the moment
Beyond the technical mechanics, the infield fly rule is a good example of something baseball does well: closing a loophole without changing the fundamental flow of the game. It doesn’t add a new out, doesn’t take away a legitimate defensive play, and doesn’t reward runners with anything they haven’t earned. It just prevents a specific, repeatable trick from being profitable. That kind of quiet fairness shows up throughout the sport’s history — from equipment standards to the rules governing who could play at all, a story told in our article on Jackie Robinson breaking baseball’s color barrier, and in the long, complicated history detailed in our piece on the Negro Leagues. If you enjoy learning how the game got to where it is today, our History & Eras hub is a good place to keep exploring, alongside pieces like the history of the World Series and how baseball changed after the steroid era.
For the official, word-for-word rule text, MLB’s rulebook is the definitive source, and it’s worth a look if you want the exact legal language behind the plain-English version above.
Frequently asked questions about the infield fly rule
Does the infield fly rule apply with a runner only on third base?
No. The rule requires force situations at both second and third base, meaning runners must be on first and second, or the bases must be loaded. A runner alone on third, or on third and first without second occupied, doesn’t create the rule’s conditions.
Can the batter be out on an infield fly even if the ball is dropped?
Yes. Once the umpire calls infield fly, the batter is out the moment the call is made, regardless of whether the ball is actually caught. If it drops, it’s still a live ball, but the out on the batter already stands.
Why doesn’t the infield fly rule apply with two outs?
Because the whole point of the rule is preventing a cheap double play. With two outs already, catching or dropping the ball only produces one more out no matter what, so there’s no trick play for the defense to exploit and no need for the rule.
Is a bunt ever called an infield fly?
No. The rule specifically excludes line drives and bunted balls, even if an infielder could catch them easily. It’s meant only for ordinary fly balls and pop-ups, not for balls that come off the bat on a low, hard, or intentionally placed trajectory.
Who decides if a pop-up counts as an infield fly?
The umpire makes the judgment call, based on whether an infielder could catch the ball with normal, ordinary effort. It’s a subjective decision made in real time, not tied to a specific distance, height, or hang time, and the umpire typically announces it while the ball is still in the air.