Bridge scoring is keeping score in contract bridge

Contract bridge

Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

. There are two common methods of scoring a single deal: "duplicate" and "rubber

Rubber bridge

Rubber bridge is a form of contract bridge and is played with four players. It is most often played for fun but is also played seriously for money...

" scoring. These two methods are similar, but differ in how the components of the score are accumulated.

In duplicate scoring, the score is a single number resulting from the addition of points awarded in accordance with either of two cases: when the contract is successful, the declaring side receives a positive score which is the sum of component points for (i) the contract itself, (ii) any overtricks, (iii) a part-score or game-score bonus, and (iv) a slam or grand slam bonus, if applicable, and the defending side receives a negative score of the same absolute value. when the contract is defeated, the defending side receives a positive score based upon the number of tricks defeated and the declaring side receives a negative score of the same absolute value.
In rubber bridge, the score is tallied by its component parts on a scoresheet divided into several segments where each partnership accumulates points either "above the line" or "below the line". Only points for a successful contract (exclusive of overtricks) are entered below the line; all other points whether for the declaring side (for overtricks, part-score or game-score bonus, slam or grand slam bonus, honours, or a bonus for making a doubled or redoubled contract ("insult"), if applicable) or the defending side (for underticks or honours, if applicable) are entered above the line.

General

In general, if the contract was made, the score consists of the following components:

• Contract points, assigned to each odd trick bid
• Bonuses, assigned for:
  • level of the contract,
  • making a doubled or redoubled contract,
• Overtrick points, assigned for each trick
  Trick-taking game
  A trick-taking game is a card game or tile-based game in which play centers on a series of finite rounds or units of play, called tricks. The object of such games then may be closely tied to the number of tricks taken, as in plain-trick games such as Whist, Contract Bridge, Napoleon, Rowboat, and...
  
   which was taken over the contracted number of odd tricks.

If the contract was not made, the side that defeated the contract receives

• Penalty points, assigned for every undertrick

Contract points

Contract points are awarded for the level of the contract, and depend on the denomination and whether the contract was doubled/redoubled (but not on vulnerability):

Denomination	Points per trick
	Undoubled	Doubled	Redoubled
No trumps	30 + an extra 10 for 1st trick	60 + an extra 20 for 1st trick	120 + an extra 40 for 1st trick
Majors Major suit In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...  ( and )	30	60	120
Minors Minor suit In contract bridge the minor suits are diamonds and clubs . They are given that name because contracts made in those suits score less than contracts made in the major suits , and they rank lower in bidding. In particular, one can make game with a bid of 4 in a major suit, while a bid of 5 is...  ( and )	20	40	80

Level bonus

There are four types of level bonus, awarded for part score, game, small slam and grand slam. A game is any contract which is worth 100 or more contract points; for example, 4, 5, 2 doubled, and 1NT redoubled are games. A part score (or partial contract) is a contract worth less than a game. The bonuses for games and slams depend on vulnerability. The part score and game bonuses apply to each hand separately in duplicate and Chicago bridge, but not in rubber bridge; in rubber bridge, a different type of "game bonus" is assigned at the end of the rubber (or at the end of the playing session if the rubber is not completed).

Level	Vulnerable	Non-vulnerable
Partscore	50	50
Game	500	300
Small slam	750	500
Grand slam	1500	1000

Slams are also games, so when scoring a slam, both game bonus and appropriate slam bonus are added. Other level bonuses are not cumulative.

Double and redouble bonus

When a (re)doubled contract is made, an additional bonus is added to the level bonus. It is colloquially referred to as an "insult", meaning that the opponents have "insulted" the pair by saying that the declarer will not make the contract. 50 points are awarded for a doubled contract made, and 100 for a redoubled contract made.

Overtrick points

When the declarer scores overtricks, each overtrick scores the same as contract points (30 for NT and major suits, 20 for minor suits) except when the contract was doubled or redoubled, in which case their value increases ("adding salt to the insult") and also depends on vulnerability:

	Vulnerable	Non-vulnerable
Doubled	200	100
Redoubled	400	200

Penalties

When the contract is defeated, regardless of its level and denomination, the only score is the penalty points assigned to the pair who defeated the contract. The penalties are summed up for every undertrick, and depend on number of undertricks, (re)double and vulnerability:

No. of undertricks	Vulnerable			Non-vulnerable
	Undoubled	Doubled	Redoubled	Undoubled	Doubled	Redoubled
1st undertrick	100	200	400	50	100	200
2nd and 3rd		300	600		200	400
4th and further		300	600		300	600

Without double and redouble, every undertrick has fixed cost of 100 or 50 points. The figures for (re)doubled undertricks are set up so that after the first vulnerable undertrick, n vulnerable undertricks cost as much as n+1 non-vulnerable ones; for example, 4 doubled undertricks non-vulnerable cost (100+200+200+300) = 800, the same as 3 undertricks vulnerable (200+300+300).

Duplicate bridge

In duplicate bridge (and the type of "friendly games" known as Chicago), all the categories are summed up, resulting in a single figure. The following table shows some examples (X denotes a double and XX a redouble):

Contract	Tricks made	Vulnera- bility	Contract points	Level bonus	(Re)double bonus	Overtrick points	Penalties	Total
2	8	any	2×30 = 60	50	-	-	-	110
2 X	8	Nvul.	2×(2×30) = 120	300	50	-	-	470
3 NT	11	Vul.	10+(3×30) = 100	500	-	2×30	-	660
1 X	8	Nvul.	2×(1×20) = 40	50	50	1×100	-	240
5 XX	12	Vul.	4×(5×30) = 600	500	100	1×400	-	1600
6 NT	13	Nvul.	10+(6×30) = 190	300 + 500	-	30	-	1020
4	7	Nvul.	-	-	-	-	3×50	–150
4 X	7	Nvul.	-	-	-	-	100+(2×200)	–500
4 X	7	Vul.	-	-	-	-	200+(2×300)	–800

Rubber bridge

Rubber bridge uses the same values for tricks, bonuses and penalties, but they are divided into two categories:

1. Below the line are entered only the contract points
2. Above the line are entered slam bonuses, "insults", overtrick points and penalties wrung from the opponents. Partscore and game bonuses are not assigned; however, a form of game bonus is added at the end of the rubber, worth 700 points if the opponents did not score a game and 500 if they did. For details, see rubber bridge
   Rubber bridge
   Rubber bridge is a form of contract bridge and is played with four players. It is most often played for fun but is also played seriously for money...
   
   .

In addition, special (rummy

Rummy

Rummy is a group of card games notable for gameplay based on the matching of similar playing cards. The Mexican game of Conquian is considered by David Parlett to be ancestral to all rummy games, which itself is derived from a Chinese game called Khanhoo and, going even further back,...

-like) bonuses (referred to as "honors") are awarded in rubber bridge for particular holdings in one hand, regardless of the outcome of the deal:

• Four out of five top trump honors (A,K,Q,J,10) in one hand are awarded 100 points;
• All five top trump honors (A,K,Q,J,10) in one hand are awarded 150 points;
• All four aces in one hand in notrump contracts are awarded 150 points.

Recent scoring changes

As of 1987, World Bridge Federation

World Bridge Federation

The World Bridge Federation is the world governing body of contract bridge. The WBF is responsible for world championship competition, most of which is conducted at a few multi-event meets on a four-year cycle...

 imposed the following scoring changes for duplicate bridge, and as of 1993 also for rubber bridge (however, since there are no official competitions, rubber bridge players accept them as they see fit):

• The undertrick penalty when doubled, not vulnerable, used to be 100 for the first undertrick and 200 for each subsequent. This was changed because it was too easy to sacrifice against a grand slam. A vulnerable grand slam is worth 1500 (slam bonus) + 500 (game bonus) + 210 (major suit
  Major suit
  In the card game contract bridge, the major suits are spades and hearts . The major suits are of prime importance for tactics and scoring as they outrank the minor suits while bidding and also outscore them...
  
  trick score) = 2210. Down 11, doubled not vulnerable, used to be 2100, a profitable sacrifice. Under the current scoring rules, down eight (-2000) would still show a profit, but down nine (-2300) would not.

Since a vulnerable small slam bid and made is worth between 1370 (6 of a minor) and 1440 (6 no trump), this change also means that for a non-vulnerable sacrifice, a result of down five (-1100) would show a profit, down six (-1400) might be a small loss or a small gain, and down seven (-1700) would be a loss. Under the old scoring rules, down seven (-1300) would have been a gain, down eight (-1500) would have been a loss.

• Also, the "insult bonus" for making a redoubled contract used to be only 50. This was changed to 100, so that playing 5 of a minor, redoubled, making an overtrick, is always worth more than an undoubled small slam.