Complete Contract Bridge Rules
Start with what a turn allows and how the game is won.
- Table
- 4 players · fixed partnerships · 52 cards · 13 each
- Bid order
- 1♣ < 1♦ < 1♥ < 1♠ < 1NT < 2♣ … < 7NT
- Release-one mode
- Independent Duplicate raw-score board practice
- Each board number determines its dealer and vulnerability. Dealer cycles N, E, S, W every four boards; vulnerability follows the WBF sixteen-board cycle. A standard 52-card pack is dealt thirteen cards each, with N–S and E–W as fixed partnerships.
- The auction starts with the dealer and proceeds clockwise. A bid combines a level from 1–7 with ♣, ♦, ♥, ♠, or NT and promises that many tricks above six. Every new bid must rank above the current bid: compare level first, then ♣ < ♦ < ♥ < ♠ < NT within a level. Pass is always legal.
- Double is legal only when the most recent non-Pass call is an opponent's bid and every intervening call is Pass. Redouble is legal only when the most recent non-Pass call is an opponent's Double and every intervening call is Pass. Any higher new bid supersedes the old doubled or redoubled status.
- Before any bid, the auction ends only with four opening passes; the board then scores 0–0 without a redeal. After a bid, three consecutive passes after the final bid end the auction. Two passes are not enough.
- Declarer is the first player on the contracting side who named the final denomination—not necessarily the player who made the last or highest-level bid. Declarer's partner is dummy and the player on declarer's left makes the opening lead. For N 1♥—E Pass—S 2♥—W Pass—N 4♥—three passes, N remains declarer, S is dummy, and E leads.
- Dummy remains hidden until the opening lead is faced; the opening leader and its AI must not see dummy beforehand. Dummy is then exposed to everyone and makes no independent decisions: declarer selects a card when the turn belongs to dummy's hand. The hand that wins a trick leads the next one, including dummy's hand.
- A trick contains one card from every hand. A player able to follow the suit led must do so; otherwise any card is legal. In a suit contract the highest trump wins, or, if no trump is played, the highest card of the suit led. NT has no trump. Ace is high down to two. The winner collects and leads the next trick.
- After thirteen tricks, undoubled contract trick points are 20 per minor-suit trick, 30 per major-suit trick, and 40 for the first NT contract trick plus 30 for each later one. Double and Redouble multiply contract trick points by two or four. A game requires at least 100 contract trick points; overtricks do not count toward that threshold.
- Made-contract bonuses are: partscore 50; game 300 non-vulnerable or 500 vulnerable; small slam 500/750; grand slam 1000/1500; doubled contract 50 and redoubled contract 100. Undoubled overtricks use denomination value. Doubled overtricks are 100 each non-vulnerable or 200 vulnerable; Redouble doubles them again.
- Undoubled undertricks cost 50 each non-vulnerable or 100 each vulnerable. Doubled non-vulnerable totals for down one/two/three/four are 100/300/500/800, then 300 more each. Doubled vulnerable totals are 200/500/800/1100, then 300 more each. Redoubled penalties are twice the doubled amounts and score to the defense.
- Exact examples1NT exactly non-vulnerable is 40 + 50 = 90; 3NT exactly is 400 non-vulnerable or 600 vulnerable; 4♠ exactly is 420/620; 6NT exactly is 990/1440; and 4♠ doubled exactly non-vulnerable is 240 + 300 + 50 = 590.
- Two edge examples2♥ redoubled making three non-vulnerable is 240 contract points + 300 game + 100 redouble bonus + 200 overtrick = 840. A doubled 4♠ contract down three gives the defense 500 non-vulnerable or 800 vulnerable. A passed-out board gives both sides zero raw score.
How to Play Contract Bridge: Your First Game
Use this order of thought to get through a complete game quickly.
- Read every contract as six plus its level. 1♥ needs seven tricks, 3NT needs nine, 4♠ needs ten, 6♦ needs twelve, and 7NT needs all thirteen. The denomination sets trump; NT means no trump suit.
- Auction legality depends on the public call history, not hand strength. A strategically poor call is still legal when it outranks the current bid and it is your turn. The AI's convention profile must never remove such a legal action.
- Do not look for dummy information before the opening lead because it is not public yet. Reassess after the lead, when one quarter of the pack becomes visible and declarer can plan entries between two hands.
- Check the suit led before playing. If your hand contains even one card of that suit, every other suit is illegal. Only a void lets you discard or ruff.
- For scoring, decide made or defeated first, then ask whether contract trick points reached 100. Do not add overtricks to the game threshold, and do not multiply game, slam, or vulnerability bonuses by Double.
- Vulnerability is a public property of the board, not something created by this table's running score. Vulnerable games and slams earn more, but vulnerable undertricks cost more, so inspect the board banner before bidding.
Contract Bridge Strategy
Move from knowing the rules to playing with a plan.
- The SAYC-lite natural-auction strategy starts with high-card points and shape: long suits suggest a trump contract, balanced hands suggest NT, and partnership fit matters more than either hand alone. It is a disclosed action-selection policy, never an auction-legality rule or a claim of complete SAYC.
- After the opening lead, declarer should plan the closed hand and dummy together: count likely losers, arrange ruffs, preserve entries, and only then decide whether to cash winners or establish a long suit.
- Defenders see dummy but not declarer's closed hand or partner's cards. Card counts, known cards, and public voids rule out impossible distributions; auction, opening-lead, and follow-order clues are only degradable soft probabilities and never let the AI read the hidden deal.
- Suit contracts often ask whether trump should be drawn first. NT contracts depend more on long suits and entries. Automatically cashing the largest card can block dummy or establish tricks in the wrong order.
- Duplicate raw score rewards reliable games and slams but punishes vulnerable doubled defeats. Whether to secure the contract or chase an overtrick should change with the contract, vulnerability, and observed distribution.
- Track the actual hand that won the current trick. The next lead comes from that hand; if dummy won, declarer selects from dummy rather than incorrectly leading from declarer's closed hand.
Contract Bridge Winning and Special Rules
Details that are easy to miss but can change the result.
- The frozen ruleset is bridge-duplicate-practice-v1. One board receives WBF Law 77 raw score independently. With no comparison table, this release has no matchpoints, IMPs, ranking, or masterpoints.
- Release one excludes Rubber and Chicago. Rubber derives vulnerability from games in a rubber; Chicago has four-deal vulnerability, carried partscores, and a fourth-deal rule. Neither may be silently combined with Duplicate board-number vulnerability.
- Release one has no claims, concessions, takebacks, or director adjustments. The interface offers only current legal actions and prevents calls or plays out of turn, revokes, insufficient bids, and illegal doubles, so real-world procedural penalties are not simulated.
- The AI's SAYC-lite profile is a uniform, disclosed selection policy. It does not alter the rules action space of 35 bids, Pass, and conditional Double/Redouble, and it does not claim every competitive sequence or convention in the ACBL SAYC booklet.
- All levels share one deterministic SAYC-lite auction policy; difficulty changes card play only. The primary Hard/Expert Wasm paths sample at most 32/64 hidden worlds with 90/180 ms soft search budgets and use exact double-dummy for the final five tricks. The intentionally weaker TypeScript degradation preserves the same public input, complete legal roots, sampler, rules, and Law 77 payoff, but uses at most 16/32 worlds and exact search only for the final three tricks; equal Wasm strength is not promised. The in-Worker chain is Wasm → TypeScript → observation-only heuristic → rules-engine legal action; if the whole Worker is unavailable, the interface uses the heuristic directly.
- Boards 1–16 have vulnerability: None, N–S, E–W, Both, N–S, E–W, Both, None, E–W, Both, None, N–S, Both, None, N–S, E–W. Board 17 repeats board 1.
- Duplicate has no honor bonus here. Double changes contract trick points, overtricks, undertricks, and the insult bonus; it never multiplies game, partscore, slam, or vulnerability bonuses as a whole.
Common Contract Bridge Rules Mistakes
The traps new players fall into most often.
- Always making the player with the last high-level bid declarer. The actual declarer is the first player on that partnership who previously named the final denomination.
- Ending after three opening passes. Before any bid, all four players must pass; after a bid, three closing passes end the auction.
- Keeping an old Double or Redouble after a new bid. The new bid supersedes that multiplier; opponents must make a new legal Double against the new contract.
- Letting the opening-lead AI see dummy early or treating dummy as a fifth autonomous player. Dummy becomes public only after the lead and is controlled by declarer.
- Discarding or ruffing while still holding the suit led. Following suit is mandatory whether or not that card can win.
- Counting overtricks toward the 100-point game threshold or multiplying the game bonus by Double. Both errors can inflate boundary contracts by hundreds of points.
- Calling a single-table raw score an IMP or matchpoint score. Both comparison systems need other results; this release explicitly has none.
- Using a four-hand double-dummy solver for ordinary hidden-information opponents. Such analysis belongs only in an explicitly labelled double-dummy or post-game tool, never in live fair play.
The Story of Contract Bridge
Where it came from, and why it turned out this way.
LineageEngland · 1920s · Whist and auction-bridge family
A partnership language with a rules boundary
Contract Bridge grew from earlier trick-taking partnerships into a game with two distinct layers: an auction that selects a contract and thirteen tricks that test it. Calls may carry agreed meanings between partners, but those conventions are strategy and disclosure, not the law that decides whether a call is legal.
Dummy changes what everyone can know
The opening lead creates Bridge's signature information shift. Dummy is still hidden before that card is faced, then becomes public to all four players. Declarer controls both partnership hands, while each defender must reason from one private hand, the auction, dummy, and cards already played.
One board, one auditable raw score
Duplicate Bridge normally compares the same deal across tables. This practice mode keeps the board number, dealer, vulnerability, and exact raw score, but does not invent matchpoints or IMPs without a comparison result. Every board therefore stands alone as a clear rules-and-play exercise.
- A complete auction has 35 ordered bids, from 1♣ through 7NT, in addition to Pass and conditional Double and Redouble.
- Dummy becomes public only after the opening lead; declarer then chooses cards from two separate hands.
- Duplicate raw score is not itself an IMP or matchpoint result: those require comparison with another result on the same board.