Where the ball is at the deciding moment makes it fair or foul.

The rule and version used here

This page applies the Official Baseball Rules, 2026 Edition, issued by the Office of the Commissioner of Baseball. The book governs Major League Baseball and MLB's professional development league system. Its 2026 change summary specifically records a clarification to the defined term “Fair Ball,” so the current 2026 wording controls this explanation.

This is not a universal baseball or softball ruling. NCAA, NFHS, international, youth, softball and tournament codes appoint their own rulebooks. Their field boundaries, replay systems and local-rule procedures may differ; use this page as the MLB baseline unless the competition has adopted the Official Baseball Rules.

The lines, bases and vertical plane are fair

Rule 2.01 places the infield and outfield, including their boundary lines, in fair territory. The Definitions of Terms describe fair territory as the area within and including the first- and third-base lines, from home base to the bottom of the fence and vertically upward. Foul territory is outside those lines.

First, second and third base are fair; a batted ball that touches any of them is a fair ball. The foul poles continue the judgment upward and count with the fair side of the boundary. “On the line” is therefore fair, not a third category.

How to judge the play in order

1. Was it touched before another test fixed its status? If so, use the ball's position when the player or umpire first touched it.
2. Did it touch a base? Contact with first, second or third base makes it fair.
3. Is it still before first or third? If untouched, wait to see where it settles or whether it bounds past a base.
4. Did it bound past first or third? It is fair if on or over fair territory as it passes; foul if on or over foul territory.
5. Did it first land on or beyond first or third? That first landing fixes fair or foul.
6. Did it leave in flight? Judge the ball against the vertical fair-territory plane, including the foul pole.
7. Then apply the consequence. Fair/foul status comes first; catches, interference, boundary awards, ground rules and replay can change what happens next.

The first bounce does not necessarily decide it

Between home and first, or home and third, an untouched batted ball is fair if it finally settles on fair ground. It is foul if it settles on foul ground. A ball can begin on either side, spin across the line several times and still be judged by its later settling, touch or passage past the base.

Home plate does not make a batted ball automatically fair or foul. MLB's current Fair Ball explanation includes a ball that bounces off home plate and then settles fair. If the same ball spins into foul territory and settles there before first or third, it is foul.

The 2026 rulebook supplies another useful boundary case: an untouched ball may hit the pitcher's plate and rebound into foul territory between home and first or third. It is foul because it has not yet reached a fair-ball deciding event.

Touching the bag and passing the bag are different tests

A batted ball that touches first or third base is fair, even if it immediately kicks into foul territory. An untouched bounding ball that misses the bag is judged by whether it is on or over fair territory when it bounds to the outfield past first or third base.

This is why a high hop can be fair without touching the line or bag: the ball may pass over the fair side of the base area while airborne. By contrast, a ball bounding past entirely on the foul side is foul. Once the ball has legally passed the deciding base area, a later bounce across the line does not reverse its status.

The first ground contact fixes the call

For an untouched ball whose first ground contact is on or beyond first or third base, that contact point controls. A fly landing on fair territory beyond the base is fair even if it then bounces into foul territory or the stands. A fly first landing in foul territory beyond the base is foul even if it then kicks back toward the field.

The line itself is fair. A ball that first strikes the chalk beyond third base is fair; dust, grass movement or the direction of the next bounce does not change the rule.

Judge the ball, then apply any contact rule

If player or umpire contact is the first event that fixes the ball's status, the Fair Ball and Foul Ball definitions use the position of the ball at that touch. A third baseman standing in foul territory can touch a ball over fair territory and make it fair. A fielder standing in fair territory can reach across the line and first touch a fly over foul territory, making it foul. A ball already fixed as fair by landing beyond a base does not become foul when it later touches someone over foul territory.

That status does not finish every ruling. A fair batted ball touching a runner or umpire can become dead and may produce an out or forced-base awards under Rules 5.06(c) and 5.09(b). A deflection by a fielder may keep the ball live. First decide fair or foul; then decide the legal effect of whom or what it touched.

The 2026 Fair Ball Comment also prevents a defender from manufacturing a foul ball: if a fielder blows on, or otherwise deliberately causes, a fair roller along the line before first or third to move foul, the umpire rules it fair and the ball remains alive.

Fair does not always mean a home run

A batted ball that leaves the playing field in flight over fair territory is fair. Under MLB's current Fair Ball guidance, a ball that directly strikes a foul pole on the fly is a home run. A fly passing outside the pole is foul.

After fair status is established, the boundary rule supplies the award. Under Rules 5.05(a)(5) and 5.06(b)(4)(A), a qualifying fair fly over the fence gives the batter and runners home, subject to touching every base. A fair ball that first touches the ground and then bounces out normally gives the batter and each runner two bases under Rules 5.05(a)(6) and 5.06(b)(4)(F). A fielder's deflection and unusual wall feature can produce a different listed award.

Uncaught, caught and tipped balls behave differently

• Uncaught foul ball: the ball is dead and runners return under Rule 5.06(c)(5). It is a strike only when the batter has fewer than two strikes.
• Foul bunt with two strikes: the batter is out under Rule 5.09(a)(4); this is the important exception to “a foul cannot be strike three.”
• Caught foul fly: the batter is out under Rule 5.09(a)(1). The catch is not converted into an ordinary dead foul ball, so runners may retouch and advance at their risk.
• Foul tip: this is not an ordinary foul ball. A sharp, direct ball from the bat that the catcher legally catches is a live strike and can be strike three.

If a fielder makes a legal catch and then steps or falls into an out-of-play area, Rule 5.06(b)(3)(C) makes the ball dead and awards each runner one base from the runner's last legally touched base when the fielder entered that area.

“If fair” remains a real condition

An infield fly is defined as a fair fly ball. Near a line, an umpire can declare “Infield Fly, if Fair.” If the untouched ball drops foul before first or third and stays foul, treat it as an ordinary foul ball; the batter is not out on the infield-fly declaration. If it drops foul and then rolls fair before passing the base, it can become a fair infield fly and the batter is out.

This is another example of two questions that should not be collapsed: the umpire can identify the potential infield fly early for the runners' protection, while final fair/foul status may remain unresolved until the ball settles, is touched or passes the base.

Only specified fair/foul calls are reviewable

MLB's current Replay Review rules allow review of a potential home run for questions including fair or foul. For a non-home-run fair/foul call, review is narrower: MLB lists a foul ruling as reviewable only when the ball first lands at or beyond the set position of the first- or third-base umpire.

A disputed slow roller near home plate is therefore not made reviewable merely because video exists. When an eligible call is changed, the replay official places the clubs as they would have been had the correct call been made. Replay changes the field ruling; it does not change the fair/foul definition.

Unusual structures need a named local ruling

Rule 4.05 permits special ground rules for field contingencies, but they cannot conflict with the Official Baseball Rules. MLB also publishes universal ground rules and permits park-specific rules for features such as railings, roofs, catwalks, ivy, padding and openings in a fence.

A local rule can decide whether contact with a particular feature leaves a ball live, creates a catch opportunity or produces a base award. It does not casually turn the foul line into foul territory. For an actual game, identify the park feature and read that game's approved ground rules before assigning an award.

Six plays under MLB's 2026 rules

1. Bunt starts foul, rolls fair and stops before first. Fair ball. The deciding fact is where the untouched ball settles, not its first bounce.
2. Grounder hits the pitcher's plate, then rebounds foul and stops before third. Foul ball. The 2026 Fair Ball Comment expressly covers this path.
3. Third baseman has both feet foul but touches a spinning ball while the ball is over the line. Fair ball. The line and the air above it are fair; the fielder's feet do not control.
4. Fly first lands fair beyond first and then bounces into the seats in foul territory. Fair ball, then dead with the normal two-base award. The fair landing comes before the boundary consequence.
5. Foul fly is legally caught while a runner is on third. Batter out; the ball stays live. The runner may score after legally retouching, subject to the defense's play or appeal.
6. Potential infield fly lands foul before third, spins fair and is untouched when it settles fair. Fair infield fly; batter out. “If Fair” was resolved by the ball's final status before third base.

Five shortcuts that produce wrong calls

• “It touched fair ground first.” Before first or third, an untouched ball can still roll foul.
• “The fielder was in foul territory.” The ball's position at first touch controls.
• “Anything touching home plate is fair.” The ball still must reach a fair-ball deciding event.
• “Fair means live forever.” A fair ball can become dead because it leaves play, lodges, or triggers another rule.
• “Every foul is dead immediately.” A caught foul fly produces an out and ordinarily leaves the ball live; a foul tip is also live.

Governing-body sources and effective version

• Office of the Commissioner of Baseball — Official Baseball Rules, 2026 Edition: Rules 2.01, 4.05, 5.05(a), 5.06(b)(3)–(4), 5.06(c)(5), 5.09(a), and Definitions of Terms
• Major League Baseball — Fair Ball, current official rule explainer
• Major League Baseball — Foul Ball, current official rule explainer
• Major League Baseball — Replay Review, current reviewable-call categories
• Major League Baseball — Ground Rules, universal and park-specific ground-rule framework

Checked on 26 August 2026 against the Office of the Commissioner's 2026 Official Baseball Rules and MLB's current live rule pages. The 2026 rulebook identifies a clarification to “Fair Ball” in its season change summary. MLB park ground rules may supplement the baseline for unusual structures; non-MLB competitions may appoint a different baseball or softball code.