31 points for a suit slam
But it's only a guide. . . you need controls
Controls, Shape, Strength. CSS
You need fewer HCP points to make a Slam in a suit, compared to making 12 tricks in NT, because you can use your shape to help. Shortages in one hand can be used to set up a ruff. Trumping your short suits in this way, in effect, can give you just as much control of a suit as Aces and Kings, provided you have sufficient spare trumps to do it.
Your approximate combined point count, including points for Distribution, should be 31+ for a Small Slam in a suit. You'll then need to know if you have 1st round controls in each suit (Ace or void). It's easy to see that if two are missing, you're unlikely to succeed in your quest to make 12 out of 13 tricks! As soon as you've established the suit you want to play in, you can ask your partner how many Aces's they've got by bidding 4NT. This is known as Blackwood , including the "Roman Key Card" variant. Cue Bidding can also sometimes be used to find controls.
Although 31 HCP + Distribution points is a reasonable guide, it's easy to see that far fewer HCP points will do the trick. For example, imagine what happens if you have all 13 spades in one hand with only rubbish in the other. That's only 10 HCP altogether. But yes, you'll make a Grand Slam in Spades. All 13 tricks.
Bidding a Slam in Suits is quite complicated for a beginner, but luckily there are many simple techniques to help you, and many advanced ones too.
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