Where did these point ranges come from?

Most bridge players are familiar with "rules" like these:

• 13 points to open the bidding
•  6 points to respond to opener
• 26 points for a game in a major suit or no trump
• 28 points for a game in a minor suit
• 33 points for a small slam
• 37 points for a grand slam

Did you ever wonder where they came from?

Consider the whole deck. Each suit has 10 HCP in it, so there are 40 HCP in the deck. There are 13 tricks in the hand, so one trick is worth about 40/13 points, or slightly more than 3 points. In other words, you can expect to take a trick for every 3 points in your hand. Let's examine some of these familiar point ranges:

 

13 points to open

With 4 players and 40 points in the deck, a 10-point hand is an average hand. If your hand is 1 trick stronger than average, you should open the bidding: 13 points.

6 points to respond to opener

Your partner's opening bid is at least 13 points, but it might be much stronger. If you have 6 points, it is likely that your side has the balance of the strength (more than 20 points between you). If that is the case, the contract likely belongs to your side. You should keep the bidding open for your partner.

26 points for a game in a major or no trump

If your side has 26 points, that is 2 tricks more than average. Half the tricks is 6 1/2. Two more is 8 1/2. OK, that's a little bit of a stretch. Still, it seems to work out. Also, the scoring bonus for making a game is usually better than the penalty for going set. It's worth stretching to bid and maybe make a game.

We require the same total strength for a no trump game (9 tricks) as for a game with a trump suit (10 tricks). That is because it is usually a little easier to take tricks with a trump suit.

28 points for a game in a minor

That seems like only 2/3 of a trick more than the requirements for a game in a major. We're stretching, again.

33 points for a small slam

With 40 points in the deck, you don't expect to be missing 2 aces if your side has 33 points. You might notice that we require 5 more points to bid six than we needed to bid five. Here, the bonus for making a slam is not so lucrative that you want to risk losing the bonus for making a game.

33 points for a small slam

With 40 points in the deck, you don't expect to be missing 1 ace if your side has 33 points.