Duplicate Bridge: How It Works, Scoring and Movements

Duplicate bridge is the form of bridge in which the same deals are played at every table, and you are scored by comparing your result with the other players who held exactly the same cards. Luck of the deal is taken out: a poor hand is poor for everyone in your seat, so only the quality of your bidding, play and defense counts.

Almost all club and tournament bridge is duplicate. If you have played at home and want to try a club game, this is what you will find there: boards instead of shuffling, bidding boxes instead of spoken bids, and a score that depends on what everyone else did.

In rubber bridge at home, the cards are shuffled for every deal. If your side gets the good cards all night, you win. Duplicate fixes that. Each deal is dealt once, kept intact in a board, and passed from table to table. By the end of the session, many pairs have played your North-South cards, and many have played East-West.

You do not need to make your contract to score well. If every North-South pair goes down two in 4♠ on a deal and you go down only one, you get a top. If everyone else makes 3NT and you make 4♥, you might also get a top, since 4♥ scores 420 against 400 for 3NT.

The rules of bridge are the same. What changes is the comparison, and that changes the strategy in many small ways.

A typical club session lasts about three hours and has 24 to 27 boards. Before you start:

1. Arrive with a partner, or ask the club for one. Most clubs help newcomers find a partner.
2. Sign in and get your table and pair number. You will either stay at your table all session or move, depending on your direction.
3. Fill in your convention card, so the opponents can see your methods.

The director announces the start. You play two to four boards against one pair (a round), then the director calls the move. Pairs that move go to their next table, and boards move as well. This repeats until the session ends.

A duplicate board is a tray with four pockets marked North, East, South and West. Each pocket holds one hand of 13 cards. The board also shows:

• The board number.
• The dealer, marked on the dealer's pocket.
• The vulnerability, usually shown by red (vulnerable) and green or white (not vulnerable) pockets.

Dealer and vulnerability follow a fixed 16-board cycle. Board 1 has North as dealer with nobody vulnerable, board 2 East as dealer with North-South vulnerable, board 3 South as dealer with East-West vulnerable, board 4 West as dealer with both vulnerable, and so on. You never shuffle a duplicate board: you take your hand from your pocket, play the deal, and put the same 13 cards back.

Many clubs now deal boards by machine before the session, which also allows a hand record: a printout of all the deals, often with a double dummy analysis of what each side can make.

Instead of speaking, each player takes a card from a bidding box and places it on the table in front of them. The cards for the auction stay out until the opening lead, so everyone can review the bidding. Passes are green cards, doubles red, redoubles blue.

When partner makes a call with a special meaning the opponents may not expect, you alert: you say "alert" and tap the alert card. For some common agreements you announce instead: after partner's 1NT opening, for example, you say the range, such as "15 to 17". The opponents may then ask what the call means. The rules for alerts are set by each national body, and your club's director can tell you the local style.

The play follows the normal rules with one difference: the cards are not gathered into tricks. Each player keeps their own cards. After each trick, you turn your card face down in front of you, pointing it lengthwise toward your side if your side won the trick and crosswise if the opponents won it. At the end, the row of cards shows who won each trick, and you can return your hand to the board in its original form.

This makes it easy to check the result, and it means the next table gets exactly the same deal.

At the end of each board, one player (usually North) enters the result. Most clubs use an electronic device on each table, such as a Bridgemate, that records the contract, declarer, the opening lead and the number of tricks, and sends them to the scoring computer. Older clubs use a paper slip that travels with each board, called a traveler. Both players check the score before the next board.

A movement is the plan that tells pairs and boards where to go after each round. There are two main types:

A Mitchell with an even number of tables needs a small adjustment (a skip or a relay table), so that pairs do not play the same boards twice. Your director handles all of this. All you need to do is check the table card or the screen before each move.

In a pairs game, each board is scored by matchpoints. On each board you compare your score with every other pair who sat in your direction:

• You get 1 matchpoint for every pair you beat.
• You get half a matchpoint for every pair you tie.

(The EBU and some other bodies use 2 for a win and 1 for a tie; the percentages come out the same.)

Here is one board played at seven tables, scored for North-South:

With seven tables, the maximum on a board (a top) is 6. Your session score is your total matchpoints as a percentage of the maximum. A score of 55% is good at most clubs, and 60% usually wins.

Look at the +450 pair. They made one overtrick more than the +420 pairs and scored 6 instead of 4. At matchpoints, every overtrick counts. That is why matchpoint players chase overtricks and choose 3NT over a minor-suit game.

In a team game, two pairs form a team of four. Your pair sits North-South at one table, and your teammates sit East-West at the other table, against the same opponents' team. The same boards are played at both tables. After the match, you compare: your North-South score at one table plus your teammates' East-West score at the other.

The difference is converted into International Match Points (IMPs) on a fixed scale. A few lines of it:

Example: North-South are vulnerable on this board. At your table, you are South and your side bids game:

At your table you make 4♠ vulnerable, +620. At the other table, your teammates sit East-West and defend 2♠, which makes ten tricks, -170 for your team. The net gain is 620 - 170 = 450 points, which is 10 IMPs.

IMPs reward safety. An undoubled overtrick is worth at most 1 IMP, but bidding a vulnerable game the other table missed is worth 10 or more. The difference in strategy is explained in matchpoints vs IMPs.

The bonuses also differ a little. In duplicate, every deal stands alone: you get 300 for a non-vulnerable game and 500 for a vulnerable one at once, and 50 for a part score. In rubber bridge, the bonus comes when you win the rubber. See bridge scoring for the full tables.

The rules. Duplicate is played under the Laws of Duplicate Bridge, written by the World Bridge Federation. National bodies such as the ACBL and the EBU add regulations: which conventions are allowed, how to alert, and how long a round takes. See the rules of bridge for the basics.

Clubs. Most clubs run open games and games for newer players, often called "novice", "0-299" or "limited" games. Start in a limited game if your club has one. The play is slower, and the director is used to questions.

Convention cards. Each pair is expected to have a filled-in convention card on the table. It lists your system, your opening bids and your leads and signals, so the opponents can see them.

Masterpoints. Good results earn masterpoints (master points in the EBU), which build into ranks. In the ACBL you need 500 masterpoints of the right mix of colors to become a Life Master. At club level, masterpoints mostly decide which limited games you may play.

Online duplicate works the same way, without the boards. A computer deals the hands, every pair plays the same set, and the scoring program compares the results at once. You can play with a human partner, or in robot tournaments where a robot partner and robot opponents fill the other seats, and you are compared with everyone who played the same deals.

BridgeDummy brings the duplicate idea into training. The Daily Challenge gives every player the same set of puzzles each day, with a leaderboard, so you see how your choices compare with the field. The puzzles come in matchpoint and IMP versions, so you can feel the difference between the two scoring methods: the hidden hands are dealt many times to fit the auction, every option is solved double dummy, and you see how others voted.