Bridge lessons · Lesson 21 of 26
Bidding a Slam
Updated 16 October 2026
A slam is a contract for twelve or thirteen of the thirteen tricks, and it earns a large bonus on top of the game bonus. Bidding one takes two checks. The two hands need about 33 points for a small slam and 37 for a grand, and the opponents must not hold two aces, which you find out with a 4NT ask called Blackwood.
How many points for a slam?
Six of anything is a small slam and needs twelve tricks. Seven is a grand slam and needs all thirteen. Just as 25 points between the two hands usually make game, a little arithmetic tells you when a slam is in reach.
These totals are for notrump, or for a suit contract once a good fit has been found. A fit of eight or more trumps makes slam easier, because a short suit can be ruffed. Find the trump suit first, then add up. If the total can reach 33, start thinking about slam. If it cannot, stop at game.
Blackwood: asking for aces
If the opponents hold two aces, they take the first two tricks and your slam is down before it starts. So before bidding six, the player planning the slam asks partner how many aces they hold. The bid that asks is 4NT, a convention called Blackwood. Partner answers at the five level.
| Answer | Aces shown |
|---|---|
| 5♣ | 0 or 4 |
| 5♦ | 1 |
| 5♥ | 2 |
| 5♠ | 3 |
The answer 5♣ can mean none or all four, but if you hold even one ace yourself, partner cannot have four. Add partner's aces to yours. Missing two aces, sign off in five of your trump suit. Missing one, bid the small slam. Holding all four, you can think about seven. A follow-up bid of 5NT then asks for kings, and partner answers in the same pattern one level higher: 6♣ for none or four, 6♦ for one, 6♥ for two, 6♠ for three. Use 5NT only when the two hands hold all four aces between them, since it commits the partnership to at least six.
When not to use Blackwood
The 4NT ask counts aces and nothing else, so some hands need another way. Two kinds of hand are the usual trouble.
The first is a hand with a void. If you hold no clubs, partner's ♣A is no use to you, but Blackwood cannot tell you which ace partner has. An answer of one ace might be the very one you do not need. The second is a hand with two quick losers in a suit. If you hold two small cards in a suit nobody has bid, the opponents may take the ace and the king of it. Blackwood shows partner's aces, never whether partner holds the king of that suit. In both cases, slow down and leave the slam to a later, more detailed tool, or settle for game.
Watch it in a deal
You are South with a big hand. Follow the two checks, points first and aces second.
North opens 1♠, you bid 2♦, a forcing new suit, and North rebids 2♠, a minimum with six spades. Your 21 plus North's 12 to 15 make 33 to 36 with a ten-card spade fit, so you check aces with 4NT. North's 5♣ shows none and you hold three, so the opponents have one ace and you bid 6♠.
The slam habit
Find a fit, then add up. When the total can reach 33, ask for aces with 4NT unless you hold a void or two quick losers in a suit. Missing two aces, stop at five. Missing one, bid six. Think about seven only with 37 points and every ace and king accounted for.
For more on the 4NT ask and its answers, see Blackwood, and for other ways to judge a slam, see slam bidding.
Practice: bidding a slam
Eight quick questions on what you just read.