Tennis Umpire Guide

At officiated matches, the chair umpire runs the contest from an elevated chair at the net, mid-court. The chair umpire is the on-court authority; a tournament referee oversees the event and handles defaults and appeals. The chair umpire's responsibilities:

Before the match:

• Inspect the court, net, and equipment. The net is 3 feet (0.914 m) high at the center and 3 feet 6 inches (1.07 m) at the posts.
• Conduct the toss — a racket spin or coin toss — to decide who serves or receives and which end each player starts on.
• Confirm the players, the format (best-of-3 or best-of-5 sets), the tiebreak rules, and the warm-up (typically 5 minutes).

During the match:

• Announce the score after every point, at the end of every game, and at the end of every set — 15, 30, 40, deuce, advantage, game, set.
• Call faults and foot faults on the serve, and call "let" on a service let.
• Enforce time: the 25-second shot clock between points, roughly 90 seconds at changeovers, 120 seconds at set breaks, and the warm-up limit.
• Rule on lets and hindrances during rallies.
• Enforce the Code of Conduct through the point-penalty ladder — warning, then point penalty, then game penalty — and refer to the referee for a possible default.
• Administer medical timeouts and bathroom breaks within the rules and manage the clock.
• Overrule line umpires when certain a call was clearly wrong, and manage challenges or electronic line calling reviews where those systems are used.
• Keep the official scorecard accurate.

After the match:

• Announce the final score.
• Sign and submit the scorecard.
• Report any code violations, retirements, or defaults to the referee.

The serve is the most heavily scrutinized action in tennis, and the umpire checks several things on every delivery:

A legal serve:

1. Behind the baseline: the server stands behind the baseline, between the imaginary extensions of the center mark and the singles (or doubles) sideline, on the correct side for the point.
2. Toss and strike: the server tosses the ball and strikes it before it lands. Swinging and missing a tossed ball is a fault, but a server may let a bad toss drop, or catch it, without penalty as long as no swing is made.
3. Into the correct box: the serve must clear the net and land in the service box diagonally opposite — deuce court to deuce court, ad court to ad court — inside the service line, center service line, and singles sideline.
4. Two attempts: the server gets a first serve and, if it faults, a second. Two faults in a row is a double fault, and the server loses the point.

Foot fault — the umpire watches the server's feet from toss to strike. It is a foot fault if, before striking the ball, the server:

• touches the baseline or the court inside it,
• steps on or over the imaginary extension of the center mark or the sideline,
• changes position by walking or running (small natural movement is allowed). A foot fault is a service fault, exactly like a serve into the net — it costs that serve, and two in a row is a double fault.

Service let — if the ball touches the net, strap, or band and still lands in the correct box, it is a let and that serve is replayed. A let on the first serve replays the first serve; a let on the second serve replays only the second. There is no limit on consecutive service lets. (Some formats, such as certain college events and past ATP experiments, play lets rather than replaying them — but the standard ITF rule replays them.)

Common service faults the umpire calls:

• Serve into the net.
• Serve landing outside the correct service box or beyond it (long or wide).
• Foot fault.
• Missing the ball entirely on the swing.
• Serving from the wrong side of the center mark, or the wrong server or order in doubles.
• (If the receiver was not ready, the serve is replayed rather than counted — not a fault.)

Tennis runs on a strict clock, and the umpire enforces it — now with a visible serve clock on most professional courts. The main limits:

Between points — 25 seconds: The server must begin the service motion within 25 seconds after the previous point ended. The umpire (or the automated serve clock) starts the count once the point is decided and the score is announced. The umpire still decides when to start the clock — for example, holding it after a long rally in hot conditions.

• Server: the first time violation is a warning; every further one costs a first serve (the server must play a second serve).
• Receiver: the first time violation is a warning; every further one is a point penalty.

Warm-up — about 5 minutes: The pre-match warm-up is limited (typically 5 minutes), and the umpire announces the time remaining.

Changeovers — about 90 seconds: Players change ends after the first game and every two games thereafter. 90 seconds is allowed at a changeover; on the very first changeover of a set the players change ends without the full sit-down. At the end of a set there is a 120-second (2-minute) set break.

Medical timeout: A player may request a medical timeout for a treatable condition. The physio evaluates, and treatment is limited (commonly one 3-minute treatment per medical condition). The umpire manages the clock and calls time.

Bathroom and change-of-attire breaks: These are limited in number and length by the tour code, and the umpire tracks them to prevent gamesmanship.

Why the clock matters to the umpire: Before the visible serve clock, "time" was a judgment call and a frequent flashpoint between players and officials. The on-court clock makes the 25-second limit objective and visible to players and spectators alike — but the timing of when to start it, and the medical, changeover, and set-break windows, remain the umpire's responsibility.

A ball is in if any part of it touches any part of the line. How that call is made depends on the level of officiating:

With line umpires:

• Each line umpire calls only their assigned line, and only "out" — with a clear voice and hand signal. A ball not called out is in. A ball is called out only when the umpire sees space between the ball and the line.
• The chair umpire may overrule a line umpire — but only promptly and only when certain the call was clearly wrong. If the chair overrules and the point cannot be reconstructed, it is replayed.
• If a line umpire is unsighted, the chair makes the call; if the chair also cannot, the point is replayed.

Challenges and electronic line calling:

• Where Hawk-Eye challenges are used, a player may challenge a limited number of times per set (commonly 3 unsuccessful challenges per set, plus one more in a tiebreak); a correct challenge is not deducted. The chair umpire calls for the review, and the ball-track animation decides.
• Electronic Line Calling (ELC / Hawk-Eye Live) replaces human line umpires entirely on many courts: cameras and sensors make the in/out call automatically and an audio "out" plays. Wimbledon removed human line judges in 2025, joining the ATP Tour and the US and Australian Opens in automated calling on main courts. Where ELC Live is used there are no challenges — the electronic call is final — and the chair umpire's focus shifts to score, time, and conduct.

Honesty note: electronic line calling is real-world officiating technology, not a JudgeMate feature. JudgeMate never calls a ball in or out — a human official makes the call, and the operator enters the resulting score.

In club, school, and recreational play (no officials): Players call their own lines, each on their own side of the net. A ball is called out only when the player clearly sees it out; any doubt goes to the opponent and the ball is good. A player cannot call a ball out on the opponent's side. This honor system — the USTA calls it "The Code" — keeps unofficiated tennis playable without a full crew.

The umpire settles who won each point. Here are the main ways a point is lost, the situations that produce a let, and how misconduct is handled.

A player loses the point when they:

• Let the ball bounce twice on their side before returning it.
• Fail to return the ball into the opponent's court — into the net, or out of bounds.
• Hit the ball before it crosses to their side of the net.
• Touch the net, net post, strap, or the opponent's court while the ball is in play.
• Deliberately touch the ball more than once with the racket, or catch or carry it.
• Are struck by a ball in play before it bounces — even when standing behind the baseline.
• Throw the racket at the ball, or drop it and it stops the ball.
• Double-fault on serve.
• Deliberately hinder the opponent.

Lets during a rally (point replayed):

• Play is stopped for a legitimate interruption — a ball rolling onto the court from elsewhere, a fallen object, an unavoidable outside hindrance.
• A service let (the serve clips the net and lands in) replays that serve.

Hindrance:

• If a player is hindered by something outside anyone's control, the point is a let.
• If a player is hindered by the opponent's deliberate act (shouting during the rally, a distracting motion), the hindering player loses the point. Unintentional hindrance (an involuntary noise, a ball falling from a pocket) is usually a let the first time — the umpire judges intent.

The Code of Conduct — the point-penalty ladder: Misconduct escalates on a fixed scale over the match:

1. Warning for the first code violation.
2. Point penalty for the second.
3. Game penalty for the third.
4. Further violations lead the umpire to call the referee, who may default the player. Code violations include audible or visible obscenity, racket or ball abuse, verbal or physical abuse, prohibited coaching, and unsportsmanlike conduct. Time violations run on their own separate track (warning, then a lost first serve for the server or a point penalty for the receiver), but both time and code violations are recorded on the scorecard.

A note on scoring format: most matches are best-of-3 sets; men's Grand Slam singles is best-of-5. A set is won at 6 games with a 2-game margin; at 6–6 a tiebreak decides it.

The umpire announces the score after every point, game, and set. The convention is simple: the server's score first, then the receiver's.

Points within a game:

• 0 is "love", then 15, 30, 40.
• 40–40 is "deuce".
• After deuce, the next point won is "advantage [player]". Win the following point to take the game; lose it and the score returns to deuce.
• Examples: "15–love", "30–15", "40–30", "deuce", "advantage server", "game server".
• Some formats use no-ad scoring — a single deciding point at deuce, with the receiver choosing the side. The umpire announces "deciding point".

Games and sets:

• A game is won at 4 points with a 2-point margin (through deuce and advantage as above).
• A set is won at 6 games with a 2-game margin; at 6–6 a tiebreak is played.
• After each game the umpire announces the game count and who leads — "game server, 4–3, first set" — and at the end of a set the set result — "game and first set, server, 6–4".

Tiebreak:

• Played to 7 points, win by 2 (so 8–6, 9–7, and so on if it reaches 6–6). Points are counted 1, 2, 3…, not 15/30/40.
• Players change ends every 6 points, and the serve rotates on a 1-2-2 pattern.
• The four Grand Slams unified a 10-point tiebreak to decide the final set (at 6–6) from 2022. The umpire calls the format and counts to 10, win by 2.

Best-of formats: most matches are best-of-3 sets; men's Grand Slam singles is best-of-5.

Announcing protocol:

• Announce the point score promptly after each point, loudly and clearly enough for the players and spectators.
• Announce the game, then the running set score, then the set and match when they are decided.
• Correct a mis-announced score before the next point begins; if a point was played to a wrong score, follow the ITF procedure for correcting it.

Running the live score with JudgeMate: JudgeMate is a free, real-time single-match live scoreboard. An umpire or scorekeeper can run the board from a phone or tablet — tap the point winner and the board updates the game, set, and match automatically, including deuce/advantage and the tiebreak, and shows the current score to players, spectators, or a stream in real time. To be clear about what it does not do: JudgeMate does not make officiating calls, track the ball, replace line umpires or electronic line calling, run draws or brackets, or keep rankings — it reflects the score the operator enters. See the tennis scoring page and try the live scoreboard. For the full scoring ladder, read how tennis scoring works, and to set the board up step by step, the tennis live scoreboard guide.

The International Tennis Federation (ITF) certifies officials internationally through a badge system, while national associations — the USTA in the United States, the LTA in Britain, the DTB in Germany, the PZT in Poland — run entry-level certification and supply officials to their events.

Entry level — national / court official:

• Start with your national federation's officiating course, covering line-umpire and chair-umpire basics: the rules, positioning, signals, foot-fault mechanics, and the Code.
• Pass a written rules exam and an on-court practical assessment.
• Work local and regional events first as a line umpire, then as a chair umpire, to build match hours.

ITF badge progression (international):

• White Badge — the entry-level ITF certification, earned through an ITF officiating school and assessment; it qualifies an official to work international events under supervision.
• Bronze, Silver, and Gold Badge — progressively higher certifications for chair umpires and referees, each requiring more experience, higher-level assessments at international tournaments, fitness and language standards, and recommendation.
• Gold Badge is the top level: Gold Badge chair umpires and referees work Grand Slams, ATP and WTA finals, and Davis Cup and Billie Jean King Cup ties.

International context: Officiating standards are unified through the ITF, but pathways into the sport begin nationally. Most national associations run introductory line-umpire courses open to club players (commonly from age 16), and the fastest route up the ladder is match volume — the more matches you work, the sooner you qualify for higher assessments.

Getting started: Contact your national tennis association's officiating department and sign up for an introductory course. Officiate locally to build experience, then apply for ITF schools as you progress. Many clubs and regional associations actively recruit and mentor new line umpires at local tournaments.