Gerber Convention
When partner opens notrump and you’ve got slam interest, you need to know how many aces they hold. That’s where Gerber comes in.
What Is Gerber?
Gerber is a jump to 4♣ that asks partner how many aces they have. It’s specifically designed for auctions where partner has opened (or rebid) in notrump.
The classic situation: partner opens 1NT, you hold a balanced hand with 17-18 points and want to explore slam. You jump to 4♣, they tell you their ace count, and you decide whether to bid 6NT.
Simple concept. But here’s the thing: most players misuse Gerber because they don’t know when it applies.
The Response Structure
Partner’s responses to 4♣ are systematic:
- 4♦ = 0 or 4 aces
- 4♥ = 1 ace
- 4♠ = 2 aces
- 4NT = 3 aces
Notice the 0 or 4 ambiguity? That’s rarely a problem. If partner opened 1NT showing 15-17 points, they’re not holding all four aces. Context tells you which it is.
After you get the answer, you can ask for kings by bidding 5♣. The responses follow the same pattern, one step higher:
- 5♦ = 0 or 4 kings
- 5♥ = 1 king
- 5♠ = 2 kings
- 5NT = 3 kings
When to Use Gerber vs. Blackwood
Here’s where players get confused. The rule is actually straightforward:
Use Gerber when partner’s last bid was in notrump.
Partner opened 1NT? Gerber applies. Partner rebid 2NT? Gerber applies. Partner jumped to 3NT? Gerber applies.
Use Blackwood when you’re in a suit auction.
If clubs have been bid naturally, if you’re looking for a suit fit, if the auction is already above 3NT, then 4NT is Blackwood, not Gerber.
Why does this matter? Because 4♣ in a suit auction is usually natural or a control bid. You can’t have the same bid mean different things.
Gerber Works Best With Balanced Hands
Gerber shines when you’re considering a notrump slam with a balanced hand. You don’t care about controls in specific suits, you just need to know the total ace count.
If you’ve got a long suit and shape, Blackwood is usually better because you’re thinking about a suit contract anyway.
Four Example Auctions
Example 1: Classic Gerber
Opener: 1NT (15-17)
Responder: 4♣ (Gerber)
Opener: 4♠ (2 aces)
Responder: 6NT
You hold ♠ KQ3 ♥ AK4 ♦ KQJ5 ♣ AJ8. Partner opens 1NT. You’ve got 20 HCP, so you know the combined count is 35-37. If partner has two aces, you’re missing only one and slam is excellent. They show two aces, you bid the slam.
Example 2: Asking for Kings
Opener: 1NT (15-17)
Responder: 4♣
Opener: 4♥ (1 ace)
Responder: 5♣ (asking for kings)
Opener: 5♠ (2 kings)
Responder: 6NT
You hold ♠ AQ ♥ AKJ7 ♦ AQJ4 ♣ K65. That’s 22 HCP. Partner shows one ace and two kings. You’re missing one ace and two kings, but the combined strength is enough for 6NT.
Example 3: Signing Off Below Slam
Opener: 1NT (15-17)
Responder: 4♣
Opener: 4♥ (1 ace)
Responder: 4NT
You hold ♠ KQ3 ♥ KQJ4 ♦ AQJ5 ♣ K8. You’ve got 19 HCP but only one ace yourself. When partner shows one ace, you’re missing two aces. Stop in 4NT.
This is one reason Gerber is nice. After hearing the response, you can stop at 4NT if slam isn’t there.
Example 4: After a 2NT Opening
Opener: 2NT (20-21)
Responder: 4♣
Opener: 4♠ (2 aces)
Responder: 5♣
Opener: 5♥ (1 king)
Responder: 7NT
You hold ♠ AK5 ♥ AKQ ♦ KQJ6 ♣ Q74. Partner shows 2 aces and 1 king. You have all four aces and three kings between you. That’s 37+ HCP and strong intermediates. Bid the grand.
When Gerber Doesn’t Apply
This is critical. Gerber only works in specific situations. It doesn’t apply when:
1. Clubs Have Been Bid Naturally
Opener: 1♣
Responder: 1♠
Opener: 3NT
Responder: 4♣
That 4♣ isn’t Gerber. It’s a natural bid, showing club length and slam interest. When a suit has been bid naturally, jumping in that suit can’t suddenly become ace-asking.
2. In Competitive Auctions
Opponent: 1♥
Partner: 1NT
Opponent: Pass
You: 4♣
This isn’t Gerber either. In competitive auctions, you need your bids to show suits and strength, not ask abstract questions. Use 4NT (quantitative) or bid naturally.
3. After Jacoby Transfers or Stayman
Partner: 1NT
You: 2♥ (transfer to spades)
Partner: 2♠
You: 4♣
You’re in a suit auction now. That 4♣ is a splinter or control bid, not Gerber. Once you’ve shown interest in a suit contract, Gerber is off.
4. When 4♣ Has Another Meaning
Some partnerships play 4♣ as South African Texas (transfer to hearts) after a 1NT opening. If that’s your agreement, Gerber isn’t available. Know what 4♣ means in your system before you bid it.
Common Mistakes
Mistake 1: Using Gerber in Suit Auctions
This is the big one. Players learn that 4♣ asks for aces, then they use it everywhere.
Opener: 1♥
Responder: 3♥
Opener: 4♣
That’s not Gerber! That’s a control bid (or shortness, depending on your methods). In a suit auction, 4NT is your ace-asking bid.
Mistake 2: Forgetting the Responses
Partner bids 4♣ Gerber, you hold three aces, and you bid… 4NT, right? Right?
Yes. But I’ve seen players forget and bid 5♣ because “three is the next step up.” No. Four responses, four steps: 4♦, 4♥, 4♠, 4NT.
Mistake 3: Using Gerber With Wildly Distributional Hands
You hold ♠ 8 ♥ KQJ9876 ♦ A4 ♣ AK5. Partner opens 1NT. Don’t bid 4♣ Gerber.
Why not? Because you’re playing in hearts, not notrump. Transfer to hearts, then use Blackwood or control bids. Gerber is for balanced slams.
Mistake 4: Bidding 5♣ for Kings When You’re Not Sure About Slam
You ask for aces, partner shows two. You’re not sure if slam is making, but you bid 5♣ to ask for kings “to get more information.”
Stop. If you’re not confident about slam after hearing the ace count, sign off at 4NT or 5NT. Asking for kings commits you to the five-level at minimum, often higher. Don’t go fishing when you should be placing the contract.
Partnership Agreements
Before you use Gerber, make sure you and partner are on the same page:
Agreement 1: Is Gerber On?
Some partnerships don’t play Gerber at all. They use 4NT as quantitative (inviting slam based on points) and don’t have an ace-asking bid over notrump. That’s fine, but you need to know.
Others play Gerber only after 1NT and 2NT openings, but not after notrump rebids. Discuss this.
Agreement 2: What About 4♣ in Other Situations?
After 1NT - 2♣ (Stayman) - 2♦ - 4♣, is that Gerber or a club slam try?
After 1NT - 2♦ (transfer) - 2♥ - 4♣, is that a splinter?
These situations come up. Have agreements.
Agreement 3: Can You Sign Off After Using Gerber?
Let’s say you bid 4♣, partner shows one ace with 4♥, and you realize slam is wrong. Can you bid 4NT to play?
Most partnerships say yes. But some treat any bid after Gerber as forcing to slam. Figure this out before it matters.
Agreement 4: Key Card Gerber
Some advanced partnerships play Key Card Gerber, where the king of trumps (if there is a trump suit) counts as a fifth “ace.” The responses change:
- 4♦ = 0 or 3 key cards
- 4♥ = 1 or 4 key cards
- 4♠ = 2 key cards without the queen
- 4NT = 2 key cards with the queen
This is uncommon, but if you play it, make sure both partners know.
The Bottom Line
Gerber is a useful tool for notrump slam auctions with balanced hands. It’s not a substitute for Blackwood in suit auctions, and it doesn’t apply in every situation where 4♣ gets bid.
Use it when partner’s last bid was notrump, you have a balanced hand, and you need to know the ace count. Learn the responses cold. And talk to your partner about when it’s on and when it’s not.
Get those agreements straight, and you’ll avoid the confused looks when you bid 4♣ and partner thinks you’re showing clubs.