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Slam Bidding in Bridge

A slam in bridge is bidding and making 12 tricks and a grand slam is bidding and making all 13 tricks. To bid a slam you need to calculate your partnerships' combined strength, just like you do when you're thinking of bidding a game.

Having 33 points between the two hands doesn't guarantee you'll make a slam but you'll make much more often than not.

On the following hand, South's simple 1♠ response paves the way to slam.

easy slam bidding

1♠ is a change of suit so it's forcing. 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.

Slam Bidding Strategy

33 points is often going to give you 12 easy tricks. Some hands with fewer than 33 points will still make slam but you'll probably need something to make up for your lack of points - perhaps a long suit or a great trump fit with a shortage in a side suit.

You might also need a suit to break nicely or perhaps even a finesse to work. 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 have a better than 50% chance of making you'll be better off in the long run than the overly cautious players. And you'll have more fun than they will.

Useful percentages to know

• 3-2 break: 68%
• 3-3 break: 35%
• Finesse: 50%
• Need two good things to happen: probably less than 50%
• Need one good thing to happen out of two: probably more than 50%

The next hand is a good slam - hearts will break 3-2 more often than not.

bridge odds

The next hand will make a grand slam if spades break or the heart finesse works.

bridge odds

An odd number of missing cards will probably break evenly. An even number of missing cards probably won't break.

You have to make a judgement call - do you trust your luck or not?

 Slam Bidding in Bridge

Quantitative 4NT

After partner's NT bid, a raise to 4NT is invitational, asking partner to bid 6NT or pass. It works in the same way that 1NT - 2NT invites partner to 3NT only this time you're interested in bidding slam rather than bidding game.

North opens 2NT to show 20-22 points and a balanced hand. South invites to slam with 4NT but North has a minimum 20 points and so passes.

inviting to slam

South's hand is the same but this time North has 22 points and is maximum for the 2NT opening. 6NT makes 6.

quantitative 4NT in bridge

Natural, invitational bids of 5 and 5♠

It's tempting to look for some gadget to get you to slam but often a simple 'have you got anything extra' bid is the way to go. An invitational bid of 5 or 5♠ solves a lot of bidding problems. ( Some partnerships like to use 5 or 5♠ as a trump quality ask. Others use it as 'do you have second round control of the unbid suit'. ) Simple is best!

Slam Bidding Conventions

2♣ opening bid

2♣ is not just forcing, in most cases it's game forcing. If you're bidding 2♣ on distributional hands without many points you won't miss many games but you'll get to a lot of games that don't make. Saving 2♣ openings for strong hands also makes your slam bidding easier.

A positive response to 2♣ is forcing to 4NT. That enables your partnership to establish a fit without fear of being left in game.

North responds 2♠ and then raises South's 3 bid to 4. North certainly doesn't want to stop in 4 but he's happy to show his hand leaving South in control.

 Slam Bidding in Bridge


The Blackwood convention, 4NT asking for aces, is useful for slam bidding when you're likely to end up in a suit contract. You'll typically have good shape to use Blackwood but with fewer than 33 points you might be missing two aces.

4NT asking for aces

4NT asks partner to show the number of Aces in his or her hand. 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.

 Slam Bidding in Bridge

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.

 Slam Bidding in Bridge

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

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 - guarantees 4 aces


The Gerber 4♣ convention is used to ask for aces after a 1NT or 2NT bid from partner.

Asking for aces - Gerber 4♣ 4NT asking for aces

Gerber 4♣ is normally used directly over a notrump bid, usually with an unbalanced hand. It is useful when you think you're strong enough for slam, but just want to be sure you're not missing 2 Aces.

After the reply, you will now be in a position to decide whether or not to bid slam. If you don't have enough aces to bid slam, you can stop in 4NT. This is a natural bid.

 Slam Bidding in Bridge

As soon as North opens the bidding, South is interested in a slam. But the 4 response shows 1 Ace and South has to be content with game.

 Slam Bidding in Bridge

This time North shows 2 Aces and South bids the slam.

Asking for Kings - 5♣

The responses are the same over 5♣ as they are over 4♣, just one level higher.

Gerber After 3NT

Most experts only use the Gerber convention 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.

This hand from a recent online game caused problems for those who tried to use Gerber. For the natural bidders there was an easy path forward after 3NT from partner. 4♣ simply showed clubs and gave plenty of room to explore for the best contract.

 Slam Bidding in Bridge

When not to ask for aces

Do you know partner's strength? Asking for aces will tell you about aces. It won't tell you if you have all the other good cards you need to make a slam!

Do you have a void? If you have a void ( no cards in a suit ) then it's likely that asking for aces won't help you. Your void means you have control of that suit anyway and if partner has the ace then it won't be pulling it's weight. Ideally you would like partner's aces to be working together with your honour cards.

Hand Evaluation

It's relatively easy to bid slam when you have plenty of high card points but you'll need good hand evaluation skills to know when slam might make with fewer points. There are two things that can be a source of extra tricks when you're short in points and they are shape and honours working together.

Honours working together

 Slam Bidding in Bridge

An Ace in one suit, King in another and Queen in a third suit is going to make a trick and maybe some more.

 Slam Bidding in Bridge

AKQJ in the same suit is four tricks. The Jack is as good as the Ace!

Some players love to ask for aces and kings but the important thing is which aces and which kings partner has, not how many.

 Slam Bidding in Bridge

Not nice

 Slam Bidding in Bridge


Don't bid bad suits with good hands!

1NT with a 5 card major

South's 1NT shows 12-14 points. North uses the Quantitative 4NT to invite to slam but South politely declines.

 Slam Bidding in Bridge

Suit Quality for Opening Bids

If you're used to the idea of bidding the lower of two 4-card suits then you might want to reconsider!

 Slam Bidding in Bridge

South opens 1 and rebids 2NT. (2 because that would be a reverse showing 4 hearts and 5 diamonds.)

 Slam Bidding in Bridge

This time South opens 1 and rebids 2NT. Those two bids show the two main features of the hand - good hearts and balanced.

Snooping in on their bidding

 Slam Bidding in Bridge

The special case of three small opposite a singleton again. It's South's job to upgrade the hand!

Different ways to show your support

Sometimes a jump to game says stop but sometimes it's a way to invite partner to slam.

Weak Freak

A jump to game by responder on the first round of bidding shows a weak hand commonly referred to as the weak freak.

 Slam Bidding in Bridge

South jumps to game to show great trumps, good shape but a weak hand.

The Delayed Game Raise

On the next hand, South changes suit and then jumps to game. That's not weak!

 Slam Bidding in Bridge

South's 2♣ is a change of suit so North can't pass. South's jump to game on the second round shows a good hand. North loves the singleton spade and the ♣Q in partner's suit.

Opener's jump to game shows strength.

 Slam Bidding in Bridge

What better way for North to show a strong hand with 4 card trumps support?

Fourth Suit Forcing

Bidding the fourth suit is forcing to game. Partner is expected to show partial support for responder's first suit or a stopper in the fourth suit. That will enable responder to choose either a 5-3 major fit or 3NT.

 Slam Bidding in Bridge

South is strong enough for game but after North's 2♣ bid it's not clear which game to be in. 2 is fourth suit forcing. North's 2NT shows something in diamonds but no partial spade support. South is happy with 3NT.

Bidding the fourth suit and then supporting partner is another way to show a good hand.

 Slam Bidding in Bridge

South's hand is strong enough for game but might not be strong enough for slam. Bidding the fourth suit puts North and South in a game forcing auction so slow shows strength - 3♠ is stronger than 4♠. North is minimum and sign off in 4♠. Danger averted!

By using fourth suit forcing, South is able to discover the singleton heart in the North hand. Three small opposite singleton is always great news!

 Slam Bidding in Bridge


Some players like to use a reverse as a 1 round force only but making it a game forcing bid helps clarify strength as well as shape.

 Slam Bidding in Bridge


 Slam Bidding in Bridge


Related Hands

Relax - You're in a slam.
Percentages - is this a good slam?


Thank you Graeme, excellent lesson on slam bidding. Enjoying your format with good everyday bidding, declarer/ defender tips & also your advanced lessons.Regards Alison
Socks says:
Fantastic lesson, this certainly spells it all out. Thank you
Hi. I played the first slam, however the 2nd set up for E-W, not N-S. I tried to change it but wouldn't work. Can you help please. Heather
Hi. I played the first 'slam' hand, the bidding wouldn't let me get passed 4H. I have just tried 3 H, I think tina and you said that bidding 3H showed a strong hand? When I bid 4H the bidding stopped. What do you say?
Pasanaa says:
A pity that you don't use RKCB. In the fourth hand the hints are to stop at 5H and it can easily make 7 if you find out the N had the KH
Pasanaa says:
Are these hands set up as ACOL?
Gits says:
Lots of homework , but good fun! Gracias!
OldDog says:
The lesson encourages an Old Dog (83) to venture up the Bridge mountain into the rarefied atmosphere of Slam bidding. Thanks
RodPerry says:
Hi, great lesson, I think though there is a typo under Gerber 5 ♣️ Asking for Kings, sorry can’t help being observant. 🥰
Hey@RodPerry. Caught my eye too. Best
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