The court lines decide more than in or out.

How to read the court during a rally

1. Identify the line or zone involved: sideline, end line, center line, attack line, service zone, free zone, or net plane.
2. Ask what rule that marking controls, such as ball in or out, service position, front-zone attack restrictions, or center-line interference.
3. For a ball landing near a boundary, remember that any contact with the relevant boundary line makes the ball in.
4. For a player-position question, judge the player's body and floor contact at the rule's required moment, not just where the ball travels.
5. Use the competition's rulebook for local facility tolerances, age-group courts, and administrative markings that can vary.

This page covers standard indoor volleyball

The measurements here describe the standard six-player indoor court used in international volleyball and followed by many national rulebooks. Beach volleyball, sitting volleyball, youth formats, recreational gyms, and modified school programs can use different court sizes or setup requirements.

Even when the facility layout varies, the basic interpretation stays consistent: use the active markings for that competition, know which lines are boundaries, and separate court dimensions from the extra clearance needed for safe play.

The playing court is 18 meters by 9 meters

The regulation indoor playing court is a rectangle 18 m long and 9 m wide. The net crosses the court at the middle, so each team defends a 9 m by 9 m court.

All court lines are normally 5 cm wide and are included in the area they mark. That detail matters for line calls: the painted boundary is not neutral space outside the court. If the ball touches any part of the correct boundary line, the ball is in.

Sidelines and end lines define in and out

The two sidelines run the length of the court, and the two end lines close the court behind each team. Together they form the playable rectangle for ball-landing decisions.

A ball that lands completely outside the boundary lines is out. A ball that touches a sideline or end line is in. Officials are not looking for where most of the ball lands; they judge whether the ball contacted the court, including the boundary line.

The center line belongs to both courts

The center line runs under the net from sideline to sideline and divides the 18 m court into two equal halves. Its axis is the reference point for each team's front zone and for many net-area judgments.

Stepping on or across the center line is not judged the same way in every situation. The important question is whether a player illegally enters the opponent's court, interferes with play, creates danger, or violates the center-line rule in the code being used. The related contact and interference calls are covered in net, center line, and overreach.

The attack line sits 3 meters from the center line

Each side has an attack line 3 m back from the center line. The area between the center line and the attack line is the front zone. The area behind the attack line is the back zone.

This line matters because back-row players and liberos have special restrictions near the net. A back-row player may attack a ball that is completely above the top of the net from behind the attack line, but attacking from the front zone can become a fault when the rule's contact and completion requirements are met. For role-specific examples, see libero and back-row attacks.

The server uses the zone behind the end line

The service zone is behind each end line. In standard indoor volleyball, it is 9 m wide, aligned with the width of the court, and extends back through the available free zone behind the court.

At service contact, the server must not touch the court or the floor outside the service zone. A jump server may take off legally from behind the end line and land inside the court after contact. The timing and foot-fault details are explained in serving faults and let serves.

The free zone is playable space outside the lines

The free zone surrounds the court and gives players room to chase balls legally. A player may run outside the boundary lines to play a ball if the ball is still live and the play is otherwise legal.

The free zone is not the same as the court. A ball landing in the free zone is out if it does not touch the boundary line, but a player standing in the free zone may still make a legal play on a ball that has not landed or touched an out-of-play object. High-level competitions often require more clearance than recreational facilities.

The legal crossing space is above the court

The net is not a boundary line on the floor, but it creates a vertical plane that matters throughout the rally. The antennas mark the sides of the legal crossing space. A ball sent to the opponent must cross over the net between the antennas unless a specific rule allows recovery outside the crossing space.

This is why a ball can be out even when it would land in the opponent's court: if it crosses outside the legal space, touches an antenna, or contacts an out-of-play object, the rally may be over before any landing decision is needed.

The line is part of the area it marks

For boundary calls, the useful shorthand is simple: line is in. A ball that clips the outside edge of a sideline or end line is in because the line belongs to the court. A ball that lands beside the line without touching it is out.

Other markings do not all work as ball-in boundaries. The attack line, center line, service-zone marks, substitution zone, and libero replacement zone control player actions or administration. They do not turn a ball landing outside the court into a live ball.

Some markings control substitutions and replacements

Volleyball courts also use zones outside the main playing rectangle for substitutions, libero replacements, team benches, warm-up areas, and scorer-table administration. Their exact markings and procedures can vary more by competition than the 18 m by 9 m court itself.

Those zones matter because a substitution or libero replacement can be illegal even when the rally space is correctly marked. The practical point is to separate live-ball court lines from administrative areas used between rallies. For lineup effects, see substitution and rotation rules.

Misunderstandings to avoid

• "The line is out" is wrong for volleyball boundaries. A ball touching a boundary line is in.
• "The free zone is part of the court" is wrong. Players may use it, but a ball landing there is out unless it touches the court boundary.
• "Crossing the center line is always a fault" is too simple. Officials look at the rulebook's interference, safety, and body-position requirements.
• "The attack line only matters to hitters" is misleading. It also affects libero setting restrictions and back-row attack judgment.
• "Every gym has the same clearance" is wrong. The court size is fixed for standard indoor play, but required run-off space can depend on the level of competition.

What officials look for

Line judges and referees use the markings as anchors. On close landings, they judge whether the ball touched the court or a boundary line. On serves, they check the server's contact point and floor position. Near the net, they watch the center line, net plane, antennas, and whether a player interfered with an opponent's play.

If a court is poorly marked, has overlapping lines for multiple sports, or lacks required clearance, the referee or event authority should identify the active volleyball markings before play. During the match, officials apply the designated competition lines rather than guessing from unused markings on the floor.

Source material

• FIVB Official Volleyball Rules
• FIVB The Game
• FIVB Basic Rules
• NCAA Playing Rules
• NFHS Volleyball Rules