Slam bidding - Gerber convention

This was first 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 was originally designed to ask for aces and kings in a no trump slam but many people prefer it to Blackwood for suit bidding. This is how it works:

The person who decides to go for a slam bids four clubs. NOTE: This has nothing to do with any clubs s/he may hold. The bidder may have no clubs or a fist full of them.

The bid means, "How many aces do you have"? The other partner MUST reply as shown here:

The reply of five clubs is very unlikely as if your partner really has all four aces you shouldn't even be in a position to ask about a slam. In practice, five clubs is used to ask for kings, (second round control), and the replies are the same but one level up as shown below:

Most players like Gerber because it keeps the bidding level low and four clubs is not a bid that would generally be heard anyway although it does happen occasionally..

Armed with the information about partner's aces and maybe kings, the Gerber instigator can decide to bid a slam or not with a reasonable chance of success.

It can be seen that Gerber keeps the bidding level lower than that achieved with Blackwood which is why it is so popular.

Blackwood convention | Cue bidding| Slam bidding