Rule of 20 in Bridge: When to Open With Less Than 13 HCP
By Bridgetastic
Quick Summary
The Rule of 20 helps decide whether to open borderline hands. Add your HCP to the length of your two longest suits, if the total is 20 or more, open the bidding.
The Formula
HCP + Length of Two Longest Suits ≥ 20 → Open
Examples
Open (Rule of 20)
♠AJ974 ♥KQ742 ♦85 ♣4
HCP: 10 + Spades: 5 + Hearts: 5 = 20 → Open 1♠
Pass (Under 20)
♠AJ74 ♥KQ74 ♦852 ♣42
HCP: 10 + Spades: 4 + Hearts: 4 = 18 → Pass
Comfortable Open
♠AKJ74 ♥Q9742 ♦K5 ♣4
HCP: 12 + Spades: 5 + Hearts: 5 = 22 → Clear Open
Why It Works
The rule captures two factors: 1. High cards, Trick-taking power 2. Distribution, Playing strength
Distributional hands play better than flat hands with the same HCP.
Comparing Hands
Hand HCP Shape Rule of 20 Open?
5-5-2-1 10 10 20 Yes
4-4-3-2 11 8 19 No
6-4-2-1 9 10 19 No
5-4-3-1 11 9 20 Yes
Adjustments
Quality Matters
With good suits, you can shade: – AKJxx + KQxxx = Better than minimum – Jxxxx + Qxxxx = Worse than it looks
Position Matters
-
1st/2nd seat: Standard Rule of 20
-
3rd seat: Can be lighter (preemptive value)
-
4th seat: Use Rule of 15 instead
Rule of 20 vs Rule of 15
Rule Used In Formula
Rule of 20 1st/2nd seat HCP + 2 longest suits
Rule of 15 4th seat HCP + spade length
Controversy
Some experts dislike Rule of 20: – “Opens too many bad hands” – “Creates rebid problems” – “Partner expects more”
Others love it: – “Gets into the auction” – “Preemptive value” – “Describes distribution”
The Rebid Problem
If you open light, plan your rebid:
♠AJ974 ♥KQ742 ♦85 ♣4
After 1♠ – 2♣, rebid 2♥ (natural, non-forcing).
Don’t get too high with minimum Rule of 20 hands!
Key Takeaways
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HCP + 2 longest suits ≥ 20
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Distribution adds value
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Suit quality matters
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Plan your rebid
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Different rules for 4th seat
See also: Rule of Fifteen (4th seat), Hand Evaluation (counting points)
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