Home / Slam Bidding - Luck, Strength, Controls

Slam Bidding

A slam in bridge requires luck, strength and controls.

slam bidding needs strength controls and luck

Luck or just playing the odds

On the following hand North opens a weak 1NT and South uses Stayman, finding the spade fit. South simply bids 6♠ which becomes the final contract. How many tricks you can make?

luck in slam bidding

By ruffing the losing heart in the North hand, declarer seems to have an easy 12 tricks as long as trumps break 3-2. So this is a slam we'd definitely be pleased to be in.

Unfortunately, when the hand was played, trumps broke 4-1. That seems pretty unlucky but a 3-2 break only happens 68% of the time. 32% of the time this well bid slam is going to go down.

If you can get used to the idea that very few slams you bid will be 100% guaranteed and, instead, aim to bid slams that simply make more often than not you'll be better off in the long run than the overly cautious players. And you'll have more fun than they do!

Strength need to bid a slam.

Slam bidding is just like bidding to game only you need extra tricks. That might sound like an over-simplification but it's not a bad way to approach things.

33 points is enough for 6NT. There are no guarantess when you're bidding in bridge but with that strength you'll make your slam more often than not.

You can often make slam in a suit contract on 30-32 points but you'll need a good trump fit and good shape. Chances are that two balanced hands ith 30 points aren't going to be enough even if you do have a trump fit.

On the following hand North and South have a natural auction to slam.

easy slam bidding

1♠ is a change of suit so it's forcing and it keeps the bidding low. That means North can't pass and is expected to describe his hand further which he does, in this case, with 2NT. That 2NT bid is a limit bid showing 18-19 points and a balanced hand. South has 15 high card points with good shape together with North's 18-19 making 33-34 between the two hands. North must have at least 2 spades for the 2NT bid so South can be sure of an 8 card trump fit. 33 points and 8 trumps.

Quantitative 4NT

Typically you need 33 HCP to bid a slam with two balanced hands because you don't have long suits to give you extra tricks. If you don't know if you're strong enough you can use the quantitative 4NT.

If the previous bid was 1NT, 2NT or 3NT then 4NT is quantitative. That's what they call it but it just mean invitational. Partner will either pass with a minimum or bid 6NT with a maximum. It's the same idea as inviting to game by bidding 2NT when partner opens 1NT.

Quantitative 4N

1N, 2N, 3N
- 4N
-- P = min
-- 6N = max

North opens 2NT, a limit bid, to show 20-22 points and a balanced hand.

quantitative 4NT in bridge

South invites to slam with 4NT. North is maximum for the 2NT opening and accepts the invitation. 6NT makes 6.

There are other sequences where you can use the Quantitative 4NT but you'll need some good agreements with your partner.

North and South are playing Acol so North's 1NT shows 12-14 points.

quantitative 4NT in bridge

South starts with Stayman, looking for a major fit. North shows spades, not what South was hoping for. What's that 4NT bid mean now?

A useful agreement when partner shows a 4-card major after Stayman is that bidding the 'other major' agrees opener's suit as trumps. South, wanting to ask for Aces with spades as trumps, would therefore bid 3 first, the other major, and then 4NT. That means the direct jump to 4NT on the hand shown is still quantitative.

On the hand shown, North is minimum and so passes. 4NT is high enough even with all those points.


If you've decided that you're strong enough to bid slam then, on some hands, it's still possible that you might be missing two aces or the Ace and King in one suit. There are various conventions you can use to check.

Cue bidding

If you and your partner have already decided on a trump suit then bidding a new suit can be used to show first or second round control in the suit. That's an Ace, King, void or singleton.

Cue bids are made as cheaply as possible. If you skip over a bid then you're denying control in that suit.

Bridge Card Game

North's 5 bid is a cue bid denying first or second round control in clubs. South bids 5♠, staying out of trouble.

Splinter bids

An unnecessary jump in a new suit can be used to show a singleton or void and a trump fit.

Bridge Card Game

4♣ showed spade support and a singleton or void in clubs. North loves that news and 6♠ makes easily.


The Gerber 4♣ convention asks for the number of aces in partner's hand.

4♣ Gerber

- 4 = 0 Ace or 4 Aces
- 4 = 1 Ace 
- 4♠ = 2 Aces 
- 4N = 3 Aces 

Most experts rarely if ever use Gerber and if they do it's only over a 1NT or 2NT bid from partner. Using Gerber after 3NT will too often take away the meaning of a natural, forcing club bid.


The Blackwood 4NT convention is one of the most commonly used bridge conventions. Blackwood is used when you are thinking of bidding a slam and want to find out how many aces partner has.

It's no good launching into Blackwood unless you've already established partner's shape and strength. Think of Blackwood as a final check to make sure you're not missing two aces rather than something you do because you can't think of any other way to explore for slam.

4NT is not a bid you would normally make in a natural sequence which makes it easy to remember that something funny is going on!

4NT asking for Aces

- 5♣ = 0 Ace or 4 Aces
- 5 = 1 Ace
- 5 = 2 Aces
- 5♠ = 3 Aces

Notice that the responses start from the lowest available bid. After hearing partner's response you will normally now be in a position to decide whether or not to bid slam.

Bridge Card Game

This hand has good trumps, honor cards in partner's suit, an excellent side suit in clubs and a singleton. Slam is a definite prospect. But partner has no aces, so slam is hopeless and you have to be content with 5♠ losing the A and the A.

Bridge Card Game

This time North shows 1 Ace and South bids the slam.

Asking for Kings

If your side has all the aces, you might like to know how many kings partner has. You should only ask for kings if you are interested in bidding a grand slam, where you need all 13 tricks. Bidding 5NT promises that no ace is missing.

5NT Asking for Kings

- 6♣ = 0 King or 4 King
- 6 = 1 King
- 6 = 2 King
- 6♠ = 3 King

Roman Key Card Blackwood

With Roman Key Card Blackwood (RKCB), 4NT asks for 'keycards' which are the 4 aces plus the King of trumps. Subsequent bidding can sometimes be used to ask if partner holds the Queen of trumps.

4NT (1430)

- 5♣ = 1 or 4 Key Cards
- 5 = 0 or 3 Key Cards
- 5 = 2 Key Cards, no TQ
- 5♠ = 2 Key Cards + TQ

When you are going to play in a suit contract the presence or absence of the trump king and trump queen are almost as important as the four aces themselves.

Bridge Card Game

5♠ shows 2 of the 5 key cards and the Q.

Trump Queen Ask

After a 5♣ or 5 respose the next step asks about the Queen of trumps. Without the Queen responder returns to the trump suit at the lowest possible level. With the Queen responder bids an outside King or simply jumps in the trump suit.

RKCB subsequent bidding

Here are some more advanced ideas to use after the initial responses to RKCB. You can leave these until you've had plenty of practice with the basic concepts.

QASK - Trump Queen Ask


- 5♣/5
-- 5/5
--- return to trump suit = no TQ
--- 5N   = TQ + 3 Kings or 0 King + 3RC
--- suit = TQ + King in that suit
--- jump in trump suit   = TQ + nothing else

KASK - King Ask

After any response, the next step that's not the trump Queen ask or sign off.


Next step 
- suit = K
- 5N = 3 Kings or 0 King + 3RC
- trumps = No K

KASK2 - Second King Ask

Cheapest non-sign off after 1 king shown by responder.
nt - asks for any second King
suit - SSA

SSA - Specific Suit Ask


- suit below trumps = that King instead
- NT below trumps = 3RC
- trumps = denies K
- trumps+1 = Kxx(x)
- trumps+2 = Kx
- Raise = KQ any length

TRCA - Third Round Control Ask

After all possible kings shown or in a suit where the K is shown or denied already
After any response if asker skips KASK or the KASK2 then a new suit is TRCA.
After KASK2


-1 = xx ( or x without 3 trumps )
-2 = Q
-raise = QJ(x)
-jump = x with 3 trumps
-sign off in trumps = xxx(x)
Jump in the trump suit = x with 3 trumps

3RC - Third Round Control

If asker has bid a side suit, shows that Q. If asker hasn’t, then it shows Q of responder’s side suit if any. Otherwise shows at least one third round control. ( any outside Q, xx or x )

tags: #slambidding

Slam bidding is hard because it doesn't happen much, not because it's hard.
Updated: 2023-12-03
Terry Gregory
Hi Graeme, most teachers avoid the issue of what 4NT means after Stayman or Transfers, because it's awkward. 4NT is quantitative. If you want to find out about aces you need extra gadgets ("...the other major" after Stayman and something like Texas Transfers.
Peter Blenkinsop
It is excellent. The only issue is that the ace asking section covers a great deal. Not sure of any answer to that complexity. Perhaps recommend a system for most and then add the 'additions' as an aside.
Ingrid Kemp
Excellent as is. The RKCB is the challenge for we Improvers/Beginners
David Paine
With RKCB I’d suggest that everything from the ‘Trump Queen Ask’ onwards should be left out and dealt with in a specific RKCB lesson.
Katy Balagopal
Very good, but for me the section on trump Q ask is a little unclear. A couple of example bidding sequences would be nice.
Rita Kumar
Great lesso, Graem, but I don’t think I’m there yet. However, I’ll try to work on it and practice it. Thanks for the lessons, examples and suggestions!
Andy Billinge
I would emphsis that Cue Bidding should pre-empt Ace asking if possible. No point in Ace asking if you have a weak side suit missing the Ace and King.
Sandy Lochhead
That's an excellent summary for slams, thank you. I use the RKCB 1430 and it seems to work quite well. I don't know many people who play Gerber so I would question whether there is the demand.
Joan Mladen
Thank you Graeme. I use RKCB 1430, but also rely on Gerber, especially when the use of RKCB makes the bidding too high too quickly and there is no way back.
Thanks, everyone, for your feedback. I've used all your ideas and the lesson seems easier to follow now. I'll add some more example hands soon.
Carol Benjamin
All clear until queen/king ask in RKC. THEN VERY CONFUSING FOR ME. Thanks.
Hi Graeme. Suggest you grade the difficulty of the strategies shown into Novice / Improver / Experienced Improver/ Intermediate. NZB have in the Transfer lesson a bid of 3-level of a Major is a SLAM try with set responses. Also there are techniques to exit Blackwood or Gerber when you partner has NOT got the number of Aces you wanted them to have. Ie you got to game by adding distribution points. Please add the strategies to "exit". Also when asked about Aces whether you count a void as an Ace. Some explanation or an example of why not would perhaps help people to remember your reason. Well done with all the different versions.
Some extra slides on common mistakes or problems. eg Using 4C as Ace asking ALWAYS must be unlearnt to start using cue bidding.

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