Slam Bidding Basics: When to Look for Slam and How to Get There Safely

You’re sitting there with 14 HCP, partner opens 1♠, you raise to 2♠, and partner jumps to 4♠. You make it, +420. Then you see the other tables are in 6♠ making for +980. That’s a 560-point swing, and you didn’t even know slam was possible.

Missing cold slams costs matchpoints and IMPs. Bidding hopeless slams costs even more. Learning when to look for slam and how to check for the right controls is one of the biggest steps you’ll take as a player.

When to Think About Slam

The basic guideline: you need around 33 points for a small slam, 37 for a grand slam. That’s true for notrump and suit contracts. But raw high card points aren’t the whole story.

Fit matters. A nine-card or ten-card fit gives you extra tricks. You can ruff losers, establish side suits, and generate tricks from distribution. With a great fit, you can make slam on 30 HCP. Without a fit, you might need 34.

Controls matter. If you have 33 HCP but the opponents can cash two aces off the top, you’re going down in 6♠. Slam bidding is about points AND controls.

Shape matters. Give me 5-5 or 6-4 distribution and 13 HCP, and I might make slam facing 18 HCP. Give me 4-3-3-3 and 16 HCP, and I probably need 19 HCP from partner.

When should you start thinking slam?

  • You’ve got 19+ HCP and partner’s opened.
  • Partner opens 2NT (20-21 HCP) and you’ve got 12+.
  • You’ve got a self-sufficient suit and 17+ HCP.
  • Partner makes a jump shift or other strong bid.

If you’re adding up the HCP and getting to 30+, don’t rush to game. Start exploring slam.

The Jump to Game Problem

You hold:

♠AQJ94
♥K3
♦AK87
♣Q5

Partner opens 1♠. You’ve got 17 HCP, a spade fit, and partner’s showing 12+. That’s at least 29 points, maybe 32 or 33. What do you bid?

Don’t bid 4♠. That shuts down the auction. Partner will pass with a minimum, and you might miss slam.

Bid something below game that shows interest: 2♦, then support spades later. Or use a conventional bid like Jacoby 2NT (game-forcing raise). Keep the auction open so partner can show extra values.

The jump to game says “this is our contract, I’m done.” If you think slam is possible, don’t do that.

Control-Showing Cuebids

You’ve agreed on a suit. You and partner both know you’re heading to game at least. Now you need to check for slam. How?

Cuebids show controls (aces and kings) in side suits. You bid a suit where you have first-round control (ace or void) or second-round control (king or singleton).

The auction:
1♠ - 3♠ (strong raise)
4♣

That 4♣ bid says “I have the club ace, do you have anything extra for slam?” It’s not saying “let’s play in clubs.” Clubs is agreed as trump.

How cuebids work:

You show first-round controls first, up the line. If you bid 4♣ and partner bids 4♦, they’re showing the diamond ace. If you then bid 4♥, you’re showing the heart ace.

If you skip a suit, you’re denying first-round control there. You bid 4♣, partner bids 4♥ (skipping diamonds). That means partner doesn’t have the diamond ace. If the opponents have two cashing diamond tricks, you need to stop in game.

After you’ve shown all first-round controls, you can go back and show kings. But most pairs stick to aces for simplicity.

Why cuebids are better than Blackwood:

Blackwood (4NT) asks for aces, and partner tells you how many. That’s great if you just need to know the number. But what if you’re missing the ace of clubs specifically and you can’t afford two quick losers there? Blackwood won’t tell you which ace partner has.

Cuebids let you zero in on the suit that matters. If you need the club ace and partner cuebids 4♣, you’re golden. If they skip clubs, you stop in game.

Blackwood: When and How

Blackwood (4NT) asks partner how many aces they have. The responses:

  • 5♣ = 0 or 4 aces
  • 5♦ = 1 ace
  • 5♥ = 2 aces
  • 5♠ = 3 aces

You use Blackwood when:

  • You’ve got a good trump fit.
  • You’ve got all suits controlled except you need to know about aces.
  • You’re not worried about a specific suit, just the raw number.

When NOT to use Blackwood:

Don’t use Blackwood with a void. If you have a void and partner shows one ace, you don’t know if it’s in your void suit (useless) or a side suit (critical). Use cuebids instead.

Don’t use Blackwood when you have a weak doubleton in an unbid suit. Partner might have zero or one ace, and opponents might have two fast tricks in your weak suit. You’ll end up in a hopeless slam.

Don’t use Blackwood when you’re just curious. You need a plan for every possible answer. If partner shows one ace, are you stopping in 5♥ or bidding 6♥? Know before you ask.

Roman Keycard Blackwood (RKCB)

Most good players use RKCB instead of regular Blackwood. It treats the king of trumps as a fifth “ace” because that king is often the difference between making slam and going down.

After 4NT, the responses are:

  • 5♣ = 0 or 3 keycards
  • 5♦ = 1 or 4 keycards
  • 5♥ = 2 keycards without the queen of trumps
  • 5♠ = 2 keycards with the queen of trumps

The five keycards are the four aces plus the king of your agreed trump suit.

Why RKCB is better:

It tells you about the trump king and trump queen, which are often critical for slam. If you’re missing the trump king, you might lose a trump trick plus a side ace. RKCB tells you immediately.

After RKCB, you can ask about kings (5NT) or the trump queen (next step up). But don’t go past your safe landing spot. If 5NT commits you to slam, make sure you want to be there.

Asking for the Trump Queen

After partner responds to RKCB, you can ask about the trump queen by bidding the next suit up (excluding trump).

Say hearts are trump:
4NT - 5♣ (0 or 3 keycards)
5♦ = asking for the queen of hearts

Partner bids:

  • 5♥ = no queen
  • 5♠ or higher = queen plus that king

This lets you fine-tune your slam decision. If you’re missing the trump queen and have eight trumps between you, you might stop in 5♥. With nine trumps, you’re probably bidding 6♥ anyway.

Grand Slam Decisions

Grand slam needs 37+ points, all four aces, the trump king, and usually the trump queen. You need to take all 13 tricks. One loser and you’re down.

When to bid 7:

  • You’ve checked for keycards and have them all.
  • You’ve got a running side suit or enormous trump fit.
  • You can count 13 tricks.

When NOT to bid 7:

  • You’re guessing.
  • You need a finesse to work.
  • You haven’t checked for the trump queen and you’re missing it.

The math on grand slam is brutal. Making 6♠ and bidding 7♠ is worth an extra 10 IMPs if you make it. Going down costs 17 IMPs. You need to be confident, not hopeful.

Most players underbid grand slams, but honestly, that’s fine. Bidding a close grand and going down is one of the worst feelings in bridge.

The Signoff Problem

You use Blackwood, partner shows one ace, and you realize slam’s not there. You bid 5♥ (your trump suit), and partner bids 6♥. What happened?

Partner thinks you were interested in grand slam. After Blackwood, a bid at the five level in the trump suit can be interpreted as “I have all the aces, do you have extra stuff for seven?”

To avoid this, make sure you and partner agree: is 5♥ after Blackwood a signoff, or is it forward-going?

Most pairs play it as a signoff. But check.

Practical Slam Bidding

Let’s walk through an auction.

You hold:

♠KQJ94
♥A3
♦AKQ5
♣72

Partner opens 1♠. You’ve got 18 HCP, a spade fit, and solid diamonds. Slam is very possible.

You bid 2♦ (natural and forcing). Partner rebids 2♠ (minimum hand, six spades). You bid 4♣ (cuebid, showing club control, but actually you’re lying—you’re checking if partner has the club ace).

Partner bids 4♦ (cuebid, showing diamond control). You bid 4NT (RKCB). Partner bids 5♦ (1 or 4 keycards). You’ve got two aces, so partner has one. That’s three keycards total (two aces plus trump king). You’re missing one ace.

You bid 6♠. You’ve got enough stuff. Even if they have the club ace, you’re probably making with those diamonds.

Common Mistakes

Rushing to Blackwood: Don’t use 4NT as the solution to every slam problem. Cuebids are often better.

Bidding past your safety level: If you use Blackwood and the answer is bad, don’t bid 6♥ anyway just because you asked.

Missing easy slams: If you have 19 and partner opens, don’t just blast to game. Explore.

Bidding slams on hope: Count your tricks. If you need a 3-3 break and two finesses to work, you’re gambling, not bidding.

Final Thoughts

Slam bidding separates good players from great ones. It’s not just about points. It’s about controls, fit, shape, and communication.

Use cuebids to pinpoint controls. Use Blackwood when you just need to count aces. Use RKCB for the trump king and queen. And don’t be a hero: if you’re missing two aces, stop in game.

Bidding a making slam feels incredible. Missing one feels terrible. But getting better at this is how you win more, and it’s one of the most satisfying parts of bridge.

Learn to sniff out slam. Check carefully. And when it’s there, bid it.

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