[wtrclr]

1c open, 1d response
3nt rebid, 4nt quantitative

Do I pass with only 19 pts and no length? what point count do I need to have, to bid 6nt?

[apollo1201]

It highly depends on what 3NT means. Usually, 18-19 bal rebids 2NT, not 3NT. I will assume it was a typo thereafter.

In all cases, besides point count, the general aspects of the hand have to be taken into account.

4333 shape is a clear minus, 4432 is fine, 5332 or 6322 is.

Fitting D honors to help establish the suit partner likely has are pluses, a small doubleton will not be so great.

Honor quality, presence of 10-9 are also positive factors.

To give an idea, I am more likely to impose slam (suggesting minor suit with 5NT maybe) with Axx Ax QJx AKT9x which is only 18, than with this so-so 19 count KQx AKJ xxx KQJx.

[DavidKok]

There are several points to discuss here. My apologies in advance if this is harsh.

• The 3NT rebid here should not show the 18-19 balanced hand. It is superior to rebid 2NT with those hands, and give partner space to describe the hand. This can help resolve inconvenient guesses at a higher level - for example over 4NT quantitative. Instead, for me, a 3NT rebid shows a solid 7(+)-card club suit and a minimum opening. By bidding more slowly we give partner space to describe their hand, so that if we are consulted on our trick-taking potential later we have more information to base that decision on. The mesh of the shapes is very important for hand evaluation.
  
• You did not mention what your agreements are about 1♦, or about alternatives (such as immediate jumps). Do you play Walsh? On this auction the answer might not matter a lot, but it also might. I'm especially curious about your agreements regarding which minor to open with balanced hands (i.e. better minor, or 1♦ 3+ (only when 4=4=3=2), or 1♦ 4+, or 1♦ [5+ or 4441], or something else?) and your agreements had partner rebid 4m (either minor) over 3NT. Being able to investigate minor suit slams - over 2NT at the 3-level, but over your jump or typo at the 4-level - reduces which hands are bidding 4NT quantitative here. In particular, I use a quantitative 4NT on a wide range of auctions, and use the space between 4NT and 6NT to look for an undiscovered fit. I'd like to know which hand types are excluded from your auction thus far, i.e. which hands we can rule out.

As apollo pointed out, the answer to a quantitative asking bid should be answered based on your trick-taking potential. This is not the same as your HCP, especially if you've had an informative auction spanning four levels of bidding space. You should therefore evaluate whether your hand is a minimum or a maximum in context.