Imprecise Precision is a strong club system, not for experts but more than just the basics. I have synthesized it from studying a variety of other systems listed in the References.

As much as possible, Imprecise Precision defines bids just one way. I don’t feel it is useful to tell someone learning a new system that they have several options for this, that, or the other.

If you are just trying Precision for the first time, you can postpone learning these portions:

This list is in order of importance for adding later.

The latter two are for hand types that are quite rare, considering that partner will have a strong club opener.

In many ways, this system is easier than 2/1 or SAYC, once you know it. The main reason to play a big club system is the improvement in your one-of-a-major openings, since those now have a limited range of 11-15 rather than 11-21. You’ll find it much easier to get to the right level and to compete.

Notrump Openings

The notrump range for Imprecise Precision is 14-16 HCP. A 14-16 NT is played exactly as you play a 15-17 NT, but responder needs one more point for his bids; for example, the invitational range is 9-10 not 8-9. You and your partner should agree upon a “runout” over opposition doubles of your 1N opener.

Other ranges are possible, most notably 12-14. If you have experience with a weak NT, you’ll know how to make the obvious changes needed.


Please see Bidding Notes for information on how to contribute, resources, acknowledgements, and a glossary. That book also contains a detailed section on notation and hand evaluation. The main things you need to know are:

  • An exclamation point after a bid means it needs to be alerted. The alert explanation follows as needed.
  • Opponents’ passes are usually omitted; their calls are shown in parentheses. Thus 1♥ - (2♠) - 4♥ means we opened 1 Heart, LHO overcalled Two Spades, and partner jumped to 4 Hearts.
  • Hand shapes that contain equal signs are in precisely spade = heart = diamond = club order. Parentheses show the shapes can be either way, as in (54)=2=2 meaning exactly two clubs and two diamonds and either 4 spades and 5 hearts or vice-versa. Hand shapes without separators can be in any suit order.

Change Log

Version 9.0 (July, 2020) Substantial rewrite and simplification

Version 8.1 (June, 2019) Minor corrections

Version 8.0 12-14 or 14-16 combined treatments.

Version 7.0 puts back the previous treatment of rattlesnakes and 2M responses to 1C.

Version 6.0 12-14 NT range instead of 14-16; improved scheme for interference.

Version 5.1 (April 2015) upgrades the HTML version to use the Alabaster theme.

Version 5.0 (January 2015) changes the preemptive and rattlesnake-related bids over one club openers. The chapter on check-back has been returned to the Advanced Bidding book. I’ve also eliminated the chapter on my conventions with local partners as we never achieved consensus.

Summary of Imprecise Precision

Imprecise Precision defines the meaning of the opening bids up to and including 2N. Openings above 2N are whatever you like – typically preempts.

We briefly describe each opening bid here. Then we cover competitive bidding and explain a special bid called Beta. The subsequent chapters fill in the details.

Strong Hands (16+ HCP)

We open 1♣! with any hand with 16+ HCP, except 16 HCP balanced hands. We also open 1♣! with a 15 HCP hand containing an excellent six-card suit and a stiff or void.

1♣! has no upper limit and absolutely may not be passed. The responses and further bids after the 1♣ opening are covered in their own chapter, Opening One Club.

Balanced Hands

Balanced hands up to 16 HCP are opened 1♦ (11-13 HCP) or 1N (14-16). Above 16 HCP they are opened 1♣!. A good 16 HCP hand with a five card suit can be opened 1♣! also.

Strong (17+ HCP) balanced hands are opened 1♣ (or 2N(20-21) if not using the Unusual 2N Opener).

Any balanced hand (with shape 4333, 4432, or 5332) is opened 1N if it has the right number of HCP. This includes hands containing a five card major. There are also 5422 hands that can be opened 1N to avoid rebid problems. It is recommended that at least one of the doubletons be Kx or better. An example is a 2=4=5=2 hand; if opened 1♦, there is no good rebid if partner responds 1♠.

Intermediate Hands (11-15 HCP)

  • 1♦ (as short as two, 11-15 HCP)

    This bid is announced as possibly as short as two cards. It helps to think of 1♦ as between a standard 1♣ and 1♦.

    With values concentrated in the minors, or balanced, 11 HCP hands should often be passed.

  • 1♥ or 1♠ (11-15 HCP)

    Shows a five card major. Because of the limited range, some responses are not standard.

  • 2♣!(11-15 HCP, 6+♣)

    This bid requires six clubs. It may contain a four- or even five-card major. However, in third seat with five good clubs we sometimes open 2♣! rather than open 1♦ and rebid 2♣.

  • 2♦!(11-15 HCP, 0-1 diamonds, no 5M, no 6♣)

    The allowed shapes are 4=3=1=5, 3=4=1=5, 4=4=1=4, 4=4=0=5. One way to remember this is “4=4=1=5 missing one card somewhere”. Another is “0 or 1 diamonds, no five card major, and no six card club suit”.

Together these bids cover all hand types. With 11-15 HCP, if you have five clubs, and no five card major, you are either short in diamonds and should open 2♦!, or you have two or more and can open 1♦ or 1N.

Preemptive Openers

  • 2♥, 2♠ are standard preemptive openers.

    Of course, they are not preemptive in fourth seat but rather show 11-15 with a six card suit.

  • 2N!(5-5 minors, preemptive)

    Shows at least 5-5 in the minors with limited strength: 4-8 HCP if not vulnerable, 8-12 HCP if vulnerable. Responses are to play except for a 3♥! inquiry.

    If not using the Heart Relay, the 2N opener reverts to the standard balanced 20-21 HCP bid.

Competitive Bidding

Most competitive bidding is identical to standard methods; with Precision you often have better information about the range of partner’s hand. You can use whatever versions of things like Michaels, Unusual 2NT, Lebensohl, etc. that you are comfortable with.

Precision-specific strategies are given in the descriptions for interference after 1♦, 2♣!, 2♦!, and 2N! openers. Interference With The One Club Opener has a chapter of its own, including Interference Over Asking Bids.


Beta is a bid peculiar to Precision. It asks for a count of Aces and Kings, counting A=2 and K=1. The responder bids steps to show how many he has:

  • The first step response corresponds to responder having no more than expected number given the auction. For example, if responder is known to hold 8+ HCP, the first step will represent 0 to 2 controls, and we will write it Beta(2).
  • The second step would be one more than the minimum, three steps for two more, etc.

Except for one case Imprecise Precision has only Beta(2) calls. That means:

  • First step is an Ace, or two Kings, or less.
  • Second step is an Ace and a King, or three Kings.
  • Third step is two Aces, an Ace and two Kings, or four Kings.
  • Fourth step shows 5 controls, etc.


In standard bidding, “count” replies to a strong 2♣ opener are similar, but not the same.

Interference with Beta is covered in Interference With Asking Bids.