The Rule of 20 tells you when a hand with fewer than 12 high card points is still worth an opening bid. Add your high card points to the number of cards in your two longest suits: if the total is 20 or more, open at the one level in first or second seat.
The rule rewards shape: two long suits take tricks that the 4-3-2-1 count does not see. If you are new to point counting, read high card points first.
How the Rule of 20 Works
Three steps, done in a few seconds:
- Count your high card points (A = 4, K = 3, Q = 2, J = 1).
- Add the length of your longest suit and your second longest suit.
- If the sum is 20 or more, open. If it is 19 or less, pass (unless you have a preempt or a weak two).
| Hand | HCP | Two longest suits | Total | Action |
|---|---|---|---|---|
| ♠KQ1063 ♥AJ852 ♦7 ♣43 | 10 | 5 + 5 | 20 | Open 1♠ |
| ♠7 ♥AQ1073 ♦KJ962 ♣84 | 10 | 5 + 5 | 20 | Open 1♥ |
| ♠A9 ♥KQ8764 ♦1072 ♣63 | 9 | 6 + 3 | 18 | Pass or weak 2♥ |
| ♠KJ4 ♥Q63 ♦QJ72 ♣K52 | 12 | 4 + 3 | 19 | Fails the rule; most players open anyway |
The last line surprises people. A flat 12 full of queens and jacks fails the rule, yet most players open every 12-count, and a few pass this one in first seat: that is style. The rule was built for the 10 and 11 point hands.
The rule is taught in 2/1, Standard American and Acol alike. Your opening still promises an ordinary opening hand.
Rule of ThumbRule of 20: HCP + cards in your two longest suits = 20 or more, open one of a suit. Many teachers add a second test: hold at least two quick tricks (two aces, AK in one suit, or an ace plus KQ in another suit).
Hands at the Border
A total of exactly 20 is a judgment call, not a green light. Upgrade or downgrade with these questions:
- Where are the honors? Points in the long suits pull their weight. Points in a singleton king or a doubleton queen do not.
- Aces and kings or queens and jacks? Aces and kings take tricks on defense and in play. A hand built on QJ holdings plays below its count.
- Do you have a sane rebid? Plan the second bid before the first. With 5-5 you open the higher suit and bid the other one next. With a five-card minor and a four-card major, check that you can show both without a reverse.
- Two quick tricks? A 20-point total with one quick trick is a hand that can go for a big penalty if partner has nothing. Some teachers use a Rule of 22: HCP + two longest suits + quick tricks must reach 22.
The rule is a minimum test. It does not replace your eyes.
First seat, nobody vulnerable. Does this hand open, and with what?
Your hand:
What Happens After You Open Light
Partner cannot tell your 10-count from a 13-count, so stay disciplined:
- Make minimum rebids. Rebid your second suit or your first suit at the lowest level. Never reverse or jump with a Rule of 20 hand.
- Decline invitations. If partner makes a limit raise or bids 2NT to invite, pass or sign off. Your hand is the bottom of the range.
- Accept some thin games. When partner has 13 and forces to game, your long suits usually cover the missing points.
Here is a typical light opening. South holds the first hand from the table.
South opens a 10-count by the Rule of 20, finds the heart fit and stops at the two level.
Dealer South, nobody vulnerable. South opens 1♠ with 10 HCP and 5-5 in the majors. Reveal to see all four hands.
North has 9 points and one spade, so North responds 1NT, forcing for one round in 2/1 (see how each system reads it). South shows the hearts and North passes with three of them. Double dummy, nine tricks are there in hearts: the 5-3 fit and the singleton replace the missing high cards. You can check this kind of claim yourself in the free double dummy analyzer.
Third and Fourth Seat
The Rule of 20 is a first and second seat rule. After partner has passed, the logic changes.
Third seat. Partner is a passed hand, so you can open lighter, even a good 9 or 10 points with a strong suit, to get in the way and direct the lead. Open 1♠ with ♠AKJ93 and little else. Do not open a ragged suit light just because the total reaches 20. Many pairs play Drury so that partner can show a fit without pushing a light opener too high.
Fourth seat. Here the choice is to open or to pass the deal out. Fourth seat has its own test, the Rule of 15 (HCP plus the number of spades), explained in Pearson points. Pass out a hand with short spades even when it passes the Rule of 20, because the opponents will outbid you in spades.
TipWant to test your opening style? The Bidding Room deals random hands and lets you bid them with EPBot robots in 2/1, SAYC, Acol, Precision or Polish Club, so you see in a few minutes how your light openings work out.
Practice: the Rule of 20
Count these before you read the answers.
- ♠AK842 ♥7 ♦Q10953 ♣82: 9 + 5 + 5 = 19. Pass in first seat.
- ♠6 ♥KQJ84 ♦AJ1052 ♣93: 11 + 5 + 5 = 21. Open 1♥, rebid 2♦.
- ♠Q2 ♥J5 ♦KQ842 ♣KJ63: 12 + 5 + 4 = 21. Open 1♦.
- ♠AQ1052 ♥3 ♦K1096 ♣742: 9 + 5 + 4 = 18. Pass, then compete later.
For more decisions with a score attached, try the bidding puzzles: you are South and pick one call, and every option is played out double dummy on many deals that fit the auction. Your answer gets 1 to 5 stars and you see how the other players voted. To go deeper into hand values, read hand evaluation and the losing trick count.