Question: How many high card points should I have to bid 2nt when my right hand opponent opens with a one bid (we’re vulnerable and opponents are not)?
Ask Gary: Unusual 2NT
The Unusual 2NT is used after the opponents open the bidding. A direct jump to 2NT shows the two lower ranking unbid suits with at least 5 cards in each suit. One of your suits will always be a minor.
For the Unusual 2NT, you should have at least 5 cards in both suits. Since there is no minimum or maximum point requirement, you should have either:
1. A weak distributional hand (less than the high-card strength for an opening bid (note: you will not respond again – you have told your story), or
2. A strong distributional hand that intends to bid again after hearing partner’s response (Typically, x x AKQJx AQJxxx). This will explain your hand to partner quicker than simply overcalling.
With an intermediate hand, you would typically make a simple overcall of the higher-ranking suit, planning to show the second suit later, if needed.
With a weak distributional hand, you are really looking for a fit and a potential sacrifice against an opponent’s game or part score. With that in mind, how many points should you have. First, the best use of the Unusual 2NT is when the opponents are vulnerable and you are not. This is the ideal time to look for a potential sacrifice. With a very weak 5-5 hand, and a poor fit with partner, the opponents will likely be playing the hand, and showing a distributional hand will only help them. Also, a very weak 5-5 hand, it will be harder for partner is assess whether to sacrifice or not and is likely to result in a too large of a penalty when he does sacrifice. Having said that, the more points you have, the less likely the opponent can make game. I would suggest points in the 6 to 10 range (xx x QJxxx K10xxx or better). If on the low end, all the points should be in your two suits.
With an opening hand, you really want to compete for the part-score. Thus, you would just overcall. If you use the Unusual 2NT with both weak and hands of opening strength, partner will be poorly placed when trying to decide how high to bid.
Now your questions about vulnerable verses non-vulnerable. I would have a very good hand (points and distribution) since there is an outside chance you might not have a fit with partner and susceptible to a large penalty. I would suggest that you should hold 6-5 distribution and reasonable suits (8 to 10 HCP) such as x x KQ10xx KJ10xxx at the least. Something in the 5 to 6 loser area assuming a reasonable fit with partner (partner or successful finesses needed to fill in the holes).