Takeout double

A double for take-out is a bid made early in an auction to indicate a willingness to compete. Such a double:

usually shows better than opening strength
promises a reasonable holding in the unbid suits - support or at least tolerance
instructs partner to bid their best suit, even if they do not hold replying strength. (Note that this isn't 100% forcing on them - in some situations partner may choose to pass for ''penalty''.)

Klinger preaches disciplined, fairly quantitative takeout doubles.

Identification

Traditionally, in order for a double to be considered takeout, it must be in the first or second round of the bidding, and neither the doubler nor their partner can have made any non-passing bid. There are however other circumstances; the Wikipedia article has more.

Takeout over the 1 level

You should hold:

16 HCP, or 12 HCP and be short in an enemy suit
7 losers or better

Such a double can be OK with as few as 10 HCP if you have 6 losers.

If you have had a chance to speak but passed, it's still OK to double for takeout if you're short in the enemy suit and have 10 HCP. Again 7 losers are expected, but 8 may be OK if you have some J/10 "filler cards".

Responses

HCP	Losers	Action
0-5	10+	If your RHO bids, pass; otherwise bid your best (least bad?) suit as cheaply as possible.
6-9	9	Bid your suit cheaply, or 1NT. Prefer major to 1NT; prefer 1NT to minor. If your RHO bids, bid anyway, but not more than one level higher than you would have.
10-12	8	Reply with a single jump - suit preference as for 6-9 HCP.
13+	7 or fewer	Bid game if a fit is clearcut; otherwise cue bid the enemy suit to force game, then go looking for the fit.

Takeout over the 2 level

Requirements are largely as per the 1 level, but a little more strength (1 fewer loser) would be wise. Responses are adjusted accordingly.

Takeout over a pre-empt

You should have:

Shortage in the enemy suit, and support or tolerance for the others.
6 or fewer losers (7 is OK in the pass-out seat).

Responses should be based on cover cards: 3 for a major game, 4 for a minor game, 5 for slam searching; if game is not indicated, bid at the cheapest level.