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The Gerber convention is a 4 response to a no-trumps bid. Like Blackwood, it is a slam investigation bid that asks partner how many aces he holds. The difference from Blackwood is that Gerber is only used for no-trumps. This is because 1NT-4NT is natural, inviting partner to bid 6NT.

When does Gerber apply? Here are some standard rules:

  • An immediate 4 response to any no-trumps bid (or overcall) is Gerber.
  • A jump rebid of 4 in response to a natural no-trump bid is Gerber.

Agreements vary widely, so make sure to discuss it with your partners.

Responses to 4

Response Meaning
4Shows 0 or 4 aces.
4 Shows 1 ace.
4 Shows 2 aces.
4NT Shows 3 aces.

Responses to 5

After hearing partner's response, the Gerber bidder can bid 5 to ask for kings.

Response Meaning
5 Shows 0 or 4 kings.
5 Shows 1 king.
5 Shows 2 kings.
5NT Shows 3 kings.


Opener   Responder
1NT (15-17)    4

Responder's hand:


Adding partner's 15-17 HCP to his own 17 HCP, responder knows that his side has 32-34 HCP. A small slam in no-trumps is possible, but the Gerber 4 bid can check if partner holds at least 2 aces.

Opener   Responder
2NT (20-21)   4

Responder's hand:


Responder is interested in 6 but doesn't want to bid it missing 2 aces. If partner shows all 4 aces, responder can bid 5 to ask for the club king, which would make 7 cold.

Opener   Responder
3NT (25-27)   4

Responder's hand:


Responder is interested in a club slam.

Opener   Responder
1NT (15-17)    21
22 4

1 Stayman, asking for a 4-card major.
2 Shows 4 hearts.

Responder's hand:


Gerber can also be used as a jump rebid after a Stayman sequence. Here, responder is interested in 6 but is missing 3 aces.

Opener   Responder
21 22
2NT (22-24)   4

1 Strong, artificial.
2 Waiting.

If a trump suit hasn't been identified yet, then 4 is Gerber after any natural no-trumps rebid.

Opener   Responder
2NT 31
3 4

1 Stayman.
2 Denies a 4-card major.

Responder's hand:


4 is NOT Gerber. It is natural because it was not a jump.

Other Considerations

  • Gerber requires a lot partnership discussion. It can get misidentified as a splinter bid (showing a club singleton/void), or as club support if partner bid clubs earlier.
  • Gerber should not be used with a void.


Gerber was invented by American expert John Gerber.

See also

  • 5NT Pick a Slam
    A conventional 5NT bid that asks partner to choose a small slam.

  • Baby Blackwood
    A conventional 3NT ace-asking bid after a major-suit fit is found.

  • Blackwood
    The original 4NT convention invented by Easley Blackwood to ask for aces.

  • Exclusion Blackwood
    A variation of Roman Key Card Blackwood that's used with a void.

  • Grand Slam Force
    A 5NT bid as a conventional grand slam try.

  • Roman Blackwood
    The Italian variation of Blackwood upon which RKCB is based. The responses to 4NT include the rank and colors of the four aces.

  • Roman Key Card Blackwood
    A popular variation of Blackwood that asks for aces and the king of trumps.

  • DEPO
    A conventional Blackwood or Gerber response after interference: Double = Even, Pass = Odd.

  • DOPI
    A conventional Blackwood or Gerber response after interference: Double = 0, Pass = 1.

  • ROPI
    A conventional Blackwood or Gerber response when the opponents double: Redouble = 0, Pass = 1.