While a deal of bridge is always played following a unique set of rules, its scoring may vary depending on the type of event the deal is played on. There are two main categories of scoring: rubber and duplicate. Rubber scoring, and its popular variant Chicago, are mostly used in social play. Duplicate scoring is focused on tournament competition and has many variations that compare and rank the relative performance of partnerships and teams playing the same deals as their competitors.
The following terms and concepts, defined in the glossary of contract bridge terms, are essential to understanding bridge scoring:
Bridge scoring consists of six to eight elements, depending on the variant.
The method of accumulation of contract points toward a "game" varies, too. However, a "game" is always triggered when 100 contract points are reached, a "partial game" or "part-score" refers to 10 to 90 contract points, and once either side reaches a game, both sides' part-scores, while still valid to be counted as part of the final score of the entire match, are reset to 0 for the purpose of the next game or rubber bonus.
This is the list of the scoring elements:
Contract points are awarded for each odd trick bid and made. Their values depend on the suit (or notrump) and whether the contract is doubled or redoubled; they are not affected by vulnerability. Tricks won beyond that necessary to fulfill the contract are referred to as overtricks and their scoring points are accounted for separately because their values are dependent upon declarer's vulnerability.
When declarer makes overtricks, their score value depends upon the contract denomination, declarer's vulnerability and whether or not the contract is undoubled, doubled or redoubled. In an undoubled contract each overtrick earns the same as in contract points (30 for notrump and major suit contracts, 20 for minor suit contracts); values increase significantly when the contract has been doubled or redoubled, especially when vulnerable.
Bonuses are awarded for all slam contracts bid and made:
When a doubled or redoubled contract is made, a bonus is awarded to the declaring side. It is colloquially referred to as a bonus for "insult", meaning that the opponents have insulted the pair by suggesting that the declarer will not make the contract.
In scoring notation, a doubled contract is indicated by an 'X" after the contract (e.g. a contract of four hearts doubled is indicated by 4♥ X); a redoubled contract is indicated by "XX" (e.g. 4♥ XX).
When a contract is defeated, penalty points are awarded to the defending side. The value of the penalty depends on the number of undertricks, whether the declaring side is vulnerable or not vulnerable and whether the contract was undoubled, doubled or redoubled.
Without a double or redouble, every undertrick has a fixed cost of 100 or 50 points. The scores for (re)doubled undertricks are such that after the first vulnerable undertrick, n vulnerable undertricks cost the same as n+1 undertricks when not vulnerable; for example, four undertricks when doubled and not vulnerable cost 800 points (100+200+200+300), the same as three undertricks when doubled and vulnerable (200+300+300).
In rubber bridge only, a bonus is awarded at the conclusion of the rubber as follows:
In rubber bridge only, a bonus is awarded for any one hand holding four or five of the honors, i.e. an ace, king, queen, jack or ten.
Honors may be declared and scored at any time after the auction but for strategic reasons it is best to do so at the conclusion of play so as not to give the opponents information about the lay of the cards. Honors may be held by any of the four players, including dummy.
In duplicate bridge only, game and partial-game bonuses are awarded at the conclusion of each deal as follows:
In four-deal bridge (Chicago) only, contract points accumulate toward a game like in rubber bridge, but game bonuses are awarded like in duplicate bridge. A separate part-score bonus is available in the fourth deal only, without accumulation.
Rubber scoring is tallied on a score sheet divided into four parts where each partnership accumulates points either above the line or below the line.
The objective is to win by scoring the most total points in the rubber; the rubber is completed when one side has twice accumulated 100 or more contract points below the line.
Only contract points are recorded below the line; all other points are recorded above the line. Any of the four players may be the recorder, his side being represented in the "We" column and the opponents in the "They" column. In the ensuing examples, South is the recorder (the 'We' on the score sheet).
The following table summarizes the results of a rubber consisting of six deals.
The following panels illustrate the progression of the scoring on the score sheet.
Deal 1: South bids 2NT making 3. Only the contract points (70) are scored below the line; the overtrick points (30) are scored above the line.
Deal 2: West bids and makes 4♥. This scores 120 contract points below the line; since there are no overtricks, no points are scored above the line. The accumulation of 100 or more points below the line constitutes the end of the first game and is signified by the drawing of a horizontal line. Since no part-game or game bonus is awarded in rubber bridge, East-West do not receive an additional game bonus and North-South do not receive any part-game bonus. Furthermore, the part score of 70 by North-South is no longer available for accumulation towards a game by them; the 70 points are said to be "cut off" as signified by the drawing of the horizontal line. Having won a game, East-West are vulnerable for all subsequent deals of the rubber meaning that they are now eligible for a larger rubber bonus if they win a second game before their opponents win one and they are susceptible to increased penalties if they are defeated in a contract.
Deal 3: West bids 5♣ and goes down 2, vulnerable, undoubled. This scores 200 penalty points for North-South above the line.
Deal 4: South bids 4♠ doubled, not vulnerable and makes 5. North-South score 240 contract tricks below the line, 100 overtrick points above the line and 50 points for 'insult' above the line. Accumulating 100 or more points below the line constitutes the end of the second game, signified by the drawing of a horizontal line. Having won a game, North-South are now also vulnerable for all subsequent deals of the rubber.
Deal 5: North bids 3♣ and makes 4 scoring 60 contract points below the line and 20 overtrick points above the line.
Deal 6: East bids and makes 6♦ - a small slam holding all five top honors. This scores a game of 120 contract points and earns a slam bonus of 750 points above the line (East-West being vulnerable). 150 honor points are scored above the line for holding all five honors. Having again accumulated 100 or more points below the line, East-West win a second game; a horizontal line is drawn to end the rubber.
Rubber Bonus: At the conclusion of the rubber, a rubber bonus is awarded. In this case, East-West have won a slow rubber and receive a 500-point rubber bonus above the line.
Total: The scores for each side are totalled and East-West (the 'They' on the score sheet) win the rubber.
Scoring in duplicate bridge is done in two stages:
In duplicate scoring, the score for each deal is independent from all others and is a single number resulting from the addition of points awarded in accordance with either of two cases:
In duplicate bridge, the dealer and the status of vulnerability for each side is predetermined by the board, there being sixteen possible combinations.
One common form of pairs scoring is by matchpoints. On each board, a partnership scores two matchpoints for each other partnership that scored fewer points with the same cards, and one point for each other partnership that scored the same number of points. Thus, every board is weighted equally, with the best result earning 100 percent of the matchpoints available, and the worst earning no matchpoints; the opponents receive the complement score, e.g. an 80% score for a N–S pair implies a 20% score for their E–W opponents. Colloquially, a maximum matchpoints score on a board is known as a "top", and a zero score is a "bottom". The terms "high board" and "low board" are also used.
These matchpoints are added across all the hands that a pair plays to determine the winner. Scores are usually given as percentages of a theoretical maximum: 100% would mean that the partnership achieved the best score on every single hand. In practice, a result of 60% or 65% is likely to win the tournament or come close. In a Mitchell movement (see above) the overall scores are usually compared separately for North–South pairs and for East–West pairs, so that there is one winner in each group (unless arrow-switching has been applied - see above).
In board-a-match team game, the matchpoints are calculated using a similar principle. Since there are only two teams involved, the only possible results are 1 (won), ½ (tied), and 0 (lost) points per board.[1]
In International Match Point (IMP) scoring,[a] the difference in total points scored (or "swing") is converted to IMPs using the standard IMP table below.[2][3] The purpose of the IMP table, which has sublinear dependency on differences, is to reduce results occurring from large swings.[4]
The score that is being compared against can be obtained in the following ways:
Example of averaged cross-IMP scoring:
Five North/South pairs play a board when vulnerable against non-vulnerable opponents. One pair makes a 4♠ contract, scoring +620, while the other North/South pairs score −100, −100, −300, and +650, respectively.
To determine the average cross-IMP score for the pair making 4♠, the table at right is created, entering the contract points scored by each pair.
Each of the other North/South's scores are subtracted from the +620 score and the result entered in the point-differential cells. For each point differential, the IMP look-up table is used to determine the IMPs gained. For example, the differential of 720 equates to 12 IMPs, because it falls in the range of 600 to 740 in the IMP table. Adding the IMPs gained gives a total of 37. To determine the average IMPs gained, divide the total by the number of competitors (37 divided by 4) to arrive at 9.25 as the averaged cross-IMP score.
In some events (for example, Swiss Teams), a further normalization to reduce the effect of large swings is applied to the International Match Point scores.
A specific number of Victory Points, either 20 or 30, are divided between the two teams in accordance with the following scales:
In the 1932 Laws of Contract Bridge, notrump tricks bid and made, and undoubled notrump tricks made but not bid, score 30, 40, 30, 40, 30, 40, 30.[5]: law 30
In 1935 this became 40, 30, 30, 30, 30, 30, 30.[6]: law 39
Redoubled undertricks have always scored twice as much as the same doubled undertricks.
A change to the scoring of the fourth and subsequent non-vulnerable undertricks, from 200 each to 300 each, was made in 1987 after a hand in the finals of the 1981 Bermuda Bowl. Munir Attaullah and Jan-e-Alam Fazli, playing for Pakistan, reached a vulnerable 7♥ contract, which would have scored them 2210. But their non-vulnerable opponent Jeff Meckstroth, playing for USA, calculated that down 11 would cost only 2100 points and thinking he might do better than that,[8] sacrificed in 7♠ on a weak hand with five spades to the jack; this was doubled and went down nine for a score of -1700. The 510 point differential resulted in an 11 IMP swing in his team's favor.
The 1987 change in scoring increased the penalty for down nine when doubled and not vulnerable from -1700 to -2300.[9]
Also, the "insult bonus" in rubber bridge 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.
It has always been the intention of every official set of Laws of Contract Bridge to forbid contracts for more than thirteen tricks. Some versions have stated this more clearly than others, but this intention of the Laws has never changed.
International Match Point scoring was first introduced at the 1938 European Championships in Oslo.[11] Its purpose is to moderate the disproportionate effect that a very large score differential (or "swing') on just one or two boards could have on the outcome of a contest involving dozens of boards.[11] The difference in total points scored by each team is converted to International Match Points (IMPs) using a standard table[2][12] which has sublinear dependencies on differences to reduce the effect of such large swings.[4]
Originally named European Match Points (EMPs),[b] the scale provided for a maximum gain of 12 points as shown in the table below. A revised table was adopted for the 1948 European Championships in Copenhagen with a maximum of 15 points. North American players were first introduced to this scoring method at the 1951 Bermuda Bowl match in Naples, Italy.[4][11]
Further revisions were made in 1961 and again in 1962 by the World Bridge Federation.[11]