Blog/Table Tennis Rules
TABLE TENNIS RULES - THE SERVE

Legal vs Illegal
Table Tennis Serves
Explained.

If your serve has never gone 16cm in the air off a flat palm, it is technically illegal. Here is the full rule.

The short answer

A legal serve requires the ball to rest on an open, flat palm, be tossed near-vertically at least 16cm, then be struck on the way down without being hidden by the server's body or arm. Most casual serves skip the toss height entirely, which makes them technically illegal - though almost never enforced outside officiated matches.

The rule exists specifically to stop servers from disguising spin by cupping the ball or serving from very close to the paddle, which used to make returns nearly impossible to read.

The 5 legality checks

1
The ball must rest on an open, flat palm
The server's free hand must hold the ball on an open palm, fingers together, before the toss - cupping or holding it with fingertips is illegal.
2
The toss must go up at least 16cm
The ball must be thrown near-vertically at least 16cm above the point it left the hand, with no spin imparted during the toss itself.
3
The ball must be struck on the way down
The server can only make contact with the ball after it has reached its highest point and started falling - hitting it on the way up is a fault.
4
The ball cannot be hidden during the serve
The server's body and free arm cannot obscure the receiver's view of the ball at any point from the toss through contact.
5
Contact must happen behind the end line
The ball must be struck behind (or over, not in front of) the server's end of the table, not inside the playing surface.

Why the toss rule exists

Before the 16cm rule was introduced, top players could serve almost directly off a low, cupped hand with heavy disguised spin, making the ball extremely difficult to read on return. Forcing a visible, minimum-height toss gives the receiver a fair chance to see the contact point and read the spin, which is exactly the intent behind the rule.

It also makes the serve a genuinely separate skill from just flicking the ball with maximum deception - a deliberate design choice by the sport's rule-makers.

Does this matter in casual play?

Almost never. The toss height rule is rarely enforced outside officiated club or tournament matches, and most recreational players have never served with a full 16cm toss in their life. It is worth knowing the rule exists mainly so you are not caught off guard the first time you play someone who serves it correctly - the ball behaves noticeably differently with a proper toss and downward strike.

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Common questions

What makes a table tennis serve illegal?
The most common issues are not tossing the ball at least 16cm, hiding the ball during the toss, or striking it on the way up instead of the way down.
Why do so many casual players serve illegally?
The 16cm toss rule is rarely enforced in casual play, so most recreational players develop a low, quick serve motion that would be called illegal under official rules.
Does an illegal serve lose the point automatically?
In officiated matches, yes. In casual, unofficiated play, this rule is almost never enforced.
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