How do I judge whether a service is legal?

Check each element of Law 2.6 (Laws of Table Tennis, ITTF Statutes 2026):

1. Ball rests freely on the open palm of the server's stationary free hand.
2. Projected near vertically upwards, without spin, rising at least 16 cm after leaving the palm, and falling without touching anything before it's struck.
3. Struck as it falls, touching the server's court then directly the receiver's court (doubles: right half-court to right half-court).
4. From the start of service until struck, the ball is above the playing surface and behind the server's end line (extended indefinitely).
5. Not hidden from the receiver by the server, the doubles partner or anything they wear or carry.
6. Free arm and hand removed from the space between the ball and the net (bounded by the ball, the net and its indefinite upward extension) as soon as the ball is projected.

Making the call

• The player must serve so that you or the assistant umpire can be satisfied it's legal. Either of you may decide a service is incorrect, and a decision by the assistant umpire on this can't be overruled by you.
• If either of you is unsure about legality, on the first occasion in the match you may interrupt play and warn the server. After that, any service by that player or their doubles partner that isn't clearly legal is incorrect.
• You may relax the requirements where you're satisfied a physical disability prevents compliance.