The 2019 laws of table tennis are part of the ITTF Handbook and can be found at pages 34-41.
The laws relating to a service are:
2.6 THE SERVICE
2.6.1 Service shall start with the ball resting freely on the open palm of the server's stationary free
2.6.2 The server shall then project the ball near vertically upwards, without imparting spin, so that it
rises at least 16cm after leaving the palm of the free hand and then falls without touching anything
before being struck.
2.6.3 As the ball is falling the server shall strike it so that it touches first his or her court and then
touches directly the receiver's court; in doubles, the ball shall touch successively the right half court
of server and receiver.
2.6.4 From the start of service until it is struck, the ball shall be above the level of the playing surface
and behind the server's end line, and it shall not be hidden from the receiver by the server or his or
her doubles partner or by anything they wear or carry.
2.6.5 As soon as the ball has been projected, the serverís free arm and hand shall be removed from
the space between the ball and the net. The space between the ball and the net is defined by the
ball, the net and its indefinite upward extension.
2.6.6 It is the responsibility of the player to serve so that the umpire or the assistant umpire can be
satisfied that he or she complies with the requirements of the Laws, and either may decide that a
service is incorrect.
18.104.22.168 If either the umpire or the assistant umpire is not sure about the legality of a service
he or she may, on the first occasion in a match, interrupt play and warn the server; but any
subsequent service by that player or his or her doubles partner which is not clearly legal
shall be considered incorrect.
2.6.7 Exceptionally, the umpire may relax the requirements for a correct service where he or she is
satisfied that compliance is prevented by physical disability.
To clarify some of the points:
The open palm means a flat hand not a cupped one (except for reasons of disability)
16 cms equates to 6.3 inches. I would recommend aiming for double that to compensate for
a lower projection in the heat of battle. As a rough guide the net post should be 15.25 cm
high so the target is approx. 1 cm / 0.5 inch more than that.
The ball must be falling when it is struck so throwing the ball onto the bat is not allowed.
The ball must be above the level of the playing service and behind the serverís end and must
not be hidden from the receiver at anytime during the service action. There is nothing in the
laws to say that the service must take place inside the imaginary extension of the table side
lines. In addition, the umpire(s) must be able to confirm that the service is legal and
therefore it is implicit that the umpire has to be able to see the ball at all times during the
If you wish to qualify as an umpire, details of the Level 1 Umpires course can be found
Tony Gregan has put this Youtube link
on the Winchester League Facebook Page which shows how to serve legally.
Now you've got no excuse!