A takeout double is a conventional double used in a competitive auction (most often, immediately after an opponent's opening bid) to show a desire to compete, in contrast to a penalty double, which indicates a desire to defend against the opponent's contract. Usually, the call indicates support for the unbid suits and a hand of opening strength or more. This call asks the doubler's partner to bid a suit, and usually implies shortness in the suit(s) doubled. Normally, a double is considered takeout only in the first round of bidding, and any subsequent ones are regarded as penalty (but see balancing double below).

In the strict sense, takeout double is a convention, as it does not show desire to penalize the opponents (which is the usual meaning of a double) ? quite the opposite. However, it is possibly the oldest bridge convention and treated as an integral part of the game, thus considered natural.

Requirements

Most common requirements to make a takeout double are:

• Shortness (doubleton or less, tripleton at most) in the opponents' suit(s),
• Length (at minimum 3 cards, preferably 4) in the unbid suits,
• High-card point strength of at least a minimal opening bid (11 HCP)

The most common treatment is that the fewer high card points the hand posesses, the distribution must be more strict (i.e. opponent's suit(s) shorter and unbid suits longer). Most players play that cards of 16(17) high card points should double regardless of distribution (unless the hand is suitable for 1NT overcall). Also, more high-card strength is required when opponents have bid on higher levels (e.g. preempted). Most players play that a double up to the level of 4♥ is takeout, while doubles on higher levels are for penalties or "cooperative" (i.e. the partner is supposed to pass unless his distribution and/or strength indicates that playing a contract of their own on a higher level is a better prospect).

Examples

1) ♠Q974 ♥9 ♦AJ93 ♣KJ85	This card is a minimal takeout double when the opponent opens 1♥. With other opening bids, it should be passed though. Also, if the opening bid was 3♥, the hand would be not strong enough to double.
2) ♠KQ83 ♥A52 ♦10 ♣AJ1062	If opponents have bid 1♦ - 1♥, the takeout double shows unbid suits (spades and clubs)
3) ♠KJ63 ♥AQ2 ♦A84 ♣Q93	With 16 balanced points, this card is suitable for 1NT overcall over any opening bid rather than for a double.
4) ♠KQJ1063 ♥AK72 ♦A4 ♣6	With 17 points and excellent spade suit, this card should double RHO's opening bid rather than overcall spades. Whatever partner bids, a subsequent bid of spades will indicate a stronger hand than a simple overcall.
5) ♠8 ♥AQ1094 ♦KJ107 ♣A83	Over an opening bid of 1♠ this hand can double or overcall 2♥ depending on style and agreements. However, over an opening bid of 1♥, it should pass, expecting to double later opponents' heart or notrump contract for penalties.

Responses

Normally, (assuming the RHO passes) the doubler's partner should make a descriptive bid indicating a long suit of his own and the high-card strength:

• A minimal-level bid of a suit indicates a weak hand (normally, below 8 high-card points).
• A jump-bid of a suit shows a long (at least a 4-card) suit and invites the partner to bid on if the double was not minimal. Normally, such bid is made with 8-11 points.
• A bid of 1NT shows 8-10 HCP and balanced hand with at least one stopper in the opponent's suit. A bid of 2NT shows 11-12 HCP and balanced hand with stopper(s).
• With any card of opening-bid strength or higher, the responder should cuebid opponent's suit. The doubler is supposed to make a descriptive bid
• Finally, the takeout double can be passed for penalties in extreme situations, when the hand has 5-6 or more excellent trumps. The doubler is supposed to lead a trump, so that the opponent's trumps can be drawn.

If the RHO bids, the doubler's partner is not forced to make a bid anymore; if one is made, it is a free bid, indicating a certain strength and/or length in the suit bid.

The strength requirements above are lowered when the partner is known to be stronger (e.g. if he doubles an opponents' preempt), and raised when partner can be weak (as in protective position).

Protective and balancing doubles

Distribution and strength requirements for a takeout double are lowered in situations when opponents' previous auction indicates that the partner has high-card strength, but was likely unable to take an action of his own because his distribution was not suitable for a double or an overcall.

A protective double can be made with as little as 8 high card points if both the RHO and the partner have passed the opening bid. Such a situation indicates that partner has strength, but was unable to act, perhaps because he had a hand like 1) or 5) in the table above:

West	North	East	South
1♥	Pass	Pass	?

South, holding ♠Q863 ♥84 ♦A85 ♣K1054 can now double, expecting to find partner with strength and likely length in hearts, allowing him to pass for penalties or make a bid.

A balancing double occurs in later rounds of bidding, in situations where opponents have found a fit, but stopped on a low level, placing some points with the partner. It is normally done with a relatively weak hand and the distribution need not be perfect.

West	North	East	South
1♣	Pass	1♥	Pass
2♥	Pass	Pass	?

South, holding ♠Q863 ♥984 ♦K1085 ♣AJ was not strong enough to double in the first round. However, he can expect the partner to have shortness in hearts and likely 4 cards in spades or diamonds and make a balancing takeout double. Such doubles are more frequent on matchpoint scoring, where even a penalty of -100 for the failure to make 2♠ can be profitable against -110 or -140 that the opponents could score in 2♥.