Gerber convention

Slam bidding convention in contract bridge
Gerber is a contract bridge convention devised by William Konigsberger and Win Nye from Switzerland who published it in 1936; John Gerber of Texas introduced it to North America in 1938 where it was named after him. It is similar to Blackwood but uses 4 instead of 4NT as a relay (asking) bid to inquire about the number of aces held by partner. A further relay bid may follow to inquire about the number of kings held. Gerber is used primarily after notrump openings, responses, and rebids, making it a complement to Blackwood rather than a replacement. Some club players also use it after suit bidding, but most experts do not recommend this.

Because bidding and making a slam or grand slam contract in bridge gains significant bonus scoring points, partnerships will strive to bid them whenever their combined card assets are deemed sufficient. Knowing the number of aces and kings jointly held is usually crucial to this decision and Gerber is one of several bridge conventions used to ascertain the necessary information.

The ace asking bid is 4. The criteria for its application vary amongst users and alternatives are detailed below; likewise, a number of response schemes have been developed over the years. Partnership agreement is required on both matters.

The main perceived advantage of Gerber is that it is bid at a lower level and therefore allows for a final contract lower than does Blackwood (in the event that insufficient aces are present). This lower level also allows for an exploration of kings in more cases. A second advantage is that it is highly suitable for potential notrump contracts, whereas with Blackwood a final contract of 5NT may be confused with a bid asking for kings. For this reason, many use Gerber when the potential contract is in notrump.