The lines define the rule, not just the drawing.

How big is a basketball court?

A full basketball court is a rectangle with a basket at each end. NBA, WNBA, and NCAA courts are commonly 94 feet long and 50 feet wide. FIBA courts are 28 meters by 15 meters, which is slightly shorter and narrower. Many U.S. high school courts are 84 feet by 50 feet, and older gyms, youth leagues, and recreational facilities may use smaller floors.

Those differences matter, but they do not change the basic rule structure. The court still has boundary lines, a midcourt line, two baskets, free-throw lanes, three-point areas where used, and marked spots for restarts, free throws, substitutions, or special administration under that rulebook.

How markings affect a call

1. Identify the exact line or marked area involved: boundary, midcourt, three-point line, free-throw line, lane, lane space, restricted area, or throw-in spot.
2. Check the player's body position, the ball's location, and whether the player is touching the line, behind the line, or airborne from a legal spot.
3. Apply the rule attached to that marking, such as out of bounds, backcourt status, three-point scoring, lane timing, free-throw restrictions, or block-charge exceptions.
4. Use the competition's diagram for exact measurements because distances and markings are not universal across all levels.
5. Administer the result: count or cancel points, award a throw-in, continue play, call a violation, or apply the relevant foul rule.

Sidelines, end lines, and out of bounds

The boundary lines are out of bounds. If a player touches a sideline or end line while holding or touching the ball, the ball is out. If the ball touches a boundary line, the floor outside the court, a backboard support, a spectator, a bench area, or another out-of-bounds object, it is also out.

The ball crossing the vertical plane of a boundary line is not enough by itself. A player may jump from inbounds, save the ball while airborne over an out-of-bounds area, and release it before landing. That is why boundary rulings usually depend on the last touch and the player's floor contact, not just where the ball appears in the air. For the possession result, see out of bounds and ball possession.

The center line and frontcourt status

The center line divides the backcourt from the frontcourt. It matters for backcourt timing, over-and-back violations, and some throw-in locations. A team that has control in its backcourt usually must advance the ball into the frontcourt within the rulebook's time limit.

Frontcourt status can be stricter than it looks near the line. During a dribble, many rulebooks require the ball and both of the dribbler's feet to be completely in the frontcourt. A player standing on the center line, straddling it, or catching the ball while touching the backcourt may not have frontcourt status yet. The full timing logic is covered in shot clock and backcourt violations.

The three-point line

The three-point line separates two-point attempts from three-point attempts. A made field goal from behind the line is worth three points. A made field goal with the shooter's foot touching the line is worth two, because the line itself is not part of the three-point area.

The distance is competition-specific. The NBA uses a longer arc with shorter corner threes. FIBA, WNBA, and NCAA courts use their own measurements, and U.S. high school courts commonly use a shorter line. On any court, officials judge the shooter's location at release. A player may jump from behind the line, release the ball, and land inside the arc after release without turning a legal three-point try into a two.

The free-throw line and lane spaces

The free-throw line marks where a foul shot is attempted. In major full-court rules, the line is about 15 feet from the plane of the backboard, with metric equivalents or diagram details depending on the code. The shooter must stay behind the line until the rulebook allows movement, usually after the ball reaches the ring or another specified point.

The marked lane spaces along the free-throw lane control who may stand near the basket during a free throw and when those players may enter. Early entry, leaving a required spot too soon, or distracting the shooter can create a free-throw violation. Those administration details connect directly to personal fouls and free throws.

The lane, key, and restricted areas

The lane, often called the paint or key, is the marked area from the end line to the free-throw line. It is used for free-throw positioning, three-second counts, rebounding position, and many plays near the basket. Lane width is not universal: NBA and WNBA lanes are wider than many NCAA and NFHS lanes, while FIBA uses metric dimensions.

Some courts also have a no-charge or restricted-area semicircle under the basket. That marking affects certain block-charge rulings, but it does not make all contact under the basket legal. The defender's position, the type of contact, whether the play is a drive or rebound, and the rulebook's exceptions still matter. For related calls, see three-second and lane violations and block or charge.

The basket, rim, and backboard

The basket is centered at each end of the court. In standard full-court basketball, the top of the rim is 10 feet above the floor. The rim, net, backboard, support, padding, and timing lights or indicators must match the competition's equipment rules.

Backboard and rim contact can affect live-ball rulings near the basket. A ball that hits the backboard remains live if no violation has occurred, but support structure contact, basket interference, goaltending, and out-of-bounds objects are separate issues. The scoring-protection rules are explained in goaltending and basket interference.

Measurements that change by rulebook

• Court length: professional, college, international, high school, youth, and recreational courts may use different lengths.
• Three-point distance: the arc and corner distance vary by level, and some younger leagues may not use a three-point line at all.
• Lane width: NBA and WNBA lanes are wider than many school and college lanes, while FIBA diagrams use metric measurements.
• Restricted-area arc: some competitions use it, some do not, and the radius and exceptions can differ.
• Hash marks and administrative spots: substitution boxes, coaching boxes, throw-in marks, and lane-space marks are rulebook-specific.

Common court-marking arguments

• "Every court is 94 by 50" is wrong. That is common for NBA, WNBA, and NCAA play, but not universal.
• "Touching the three-point line still counts as three" is wrong. A foot on the line makes the try a two-point attempt.
• "The ball is out when it passes the sideline" is wrong. It must touch something out of bounds, or be touched by a player who is out of bounds.
• "The restricted arc decides every charge" is too simple. It only answers part of certain block-charge plays.
• "Paint means the same thing in every rule" is misleading. The lane, free-throw lane, restricted area, no-charge arc, and lane spaces have related but different jobs.

What officials look for

Officials use court markings as visual anchors. On a three-point try, they check whether the shooter's foot was on or behind the arc at release. On boundary plays, they watch the player's feet, the line, and the final touch. On lane and free-throw plays, they watch marked spaces and timing restrictions.

If a court has an unusual layout, missing line, temporary tape, or overlapping markings for multiple sports or age groups, officials and game administrators should identify the active lines before play begins. Once the game starts, officials enforce the markings designated for that competition, not a different line painted for another level.

Source material

• NBA Rule No. 1: Court Dimensions - Equipment
• FIBA Official Basketball Rules
• Official Rules of the WNBA
• NCAA Basketball Rules
• NFHS Basketball Rules