Theory and Conventions


M J Bridge



Beginner and above

Rules of 18, 19, and 20

There are various rules which apply to most organised bridge in England.

These are regulations which have been laid down, basically to create a level playing field.  They are, not infrequently, broken, usually unwittingly and with no intention to cheat.  In a friendly game at home it really doesn’t matter, but if at some time in the future you find yourself playing bridge at a higher level then you will wish that you had learned these rules at some earlier point.

For the moment I am concerned only with those rules which affect the legality of an opening bid.

There are those who feel that such rules should not exist and that you should be allowed to open whatever you like on whatever you like in a totally random manner.  Certainly this will leave the opposition without any logical defensive method, but more importantly it will also leave partner at a loss.  The possibility of any sort of constructive bidding dialogue will have disappeared, and with it much of what makes bridge such a great game.

Broadly speaking these rules define minimum permitted strengths for various types of opening bid, and also place some further restrictions on artificial opening bids.

These rules have names along the lines of ‘rule of (number)’.  In each case the total when you add the number of high card points in the hand to the lengths of the two longest suits must equal or exceed the given number.

For example, on a hand with nine high card points and 5-4 shape, the total would come to eighteen.

Such a hand would be sufficient to make any bid which required (for example) ‘rule of eighteen’, but not one which required ‘rule of nineteen’.

K 5

8 7 3

A J T 7 4 2


Nine points and 6-3 shape.  This gives a total of eighteen.

It would be legal to open this hand with one of a suit in a situation in which ‘rule of eighteen’ applies (level 4),

but not if the requirement is ‘rule of nineteen’ (level 2).

Rule of eighteen

For a hand to satisfy the ‘rule of eighteen’ the total of high card points together with the number of cards in the two longest suits must come to eighteen or more.

At level four any opening bid of one of a suit must contain at least eight points, and if the bid is made in first or second seat it must also satisfy the ‘rule of eighteen’.

Rule of nineteen

For a hand to satisfy the ‘rule of nineteen’ the total of high card points together with the number of cards in the two longest suits must come to nineteen or more.

At level two any opening bid of one of a suit must either contain at least eleven points, or a minimum of eight points and satisfy the ‘rule of nineteen’.

Rule of twenty

This is not a rule laid down in the regulations.  It is no more than a guideline to good bidding practice.

The guideline that you should open most hands which satisfy ‘rule of twenty’ is an excellent starting point.

In practice this means that with eleven points and 5-4 shape you should open one of a suit more often than not.

Clearly such hands will satisfy both ‘rule of eighteen’ and ‘rule of nineteen’ and so the opening bid will be legal at either level two or level four.

However, it is a ‘rule’ which may (and on occasion, should) be broken.  There are ‘rule of twenty’ hands which are better left unopened, and there are hands which should be opened on less than ‘rule of twenty’.

Applying the rules

An example of how these rules apply at level two is:-

you can open a 6-4 or a 5-5 shape with as few as nine points if that is your agreed method;

but you cannot open a 5-4 shape with less than ten points.

This page last revised 1st Mar 2020

Context  -  The opening bid.