Contract Success Rate
Two good hands do not always make a game. After a board where the contract failed, or while judging how high to bid with partner, a player often wants to know whether the contract was a sound bet or simply unlucky. The contract success rate tool settles that by dealing out the unseen cards many times and counting how often the contract comes home.
What the contract success rate tool does
The BridgeTricks contract success rate tool takes your North and South hands and a contract, deals the other 26 cards to the opponents 1,000 random ways, plays every deal double dummy and reports the percentage of deals on which the contract makes. It also shows the spread of tricks taken.
A double dummy result answers a question about one fixed deal. This tool asks how often the contract makes across the layouts the opponents might hold. The result is the chance the contract makes, a percentage you can set against the odds a game or a slam needs.
Each run costs 1 credit, so it needs an account. The tool sits with the Deal Analysis tools, next to the double dummy solver.
How to use it
- 1.Open the contract success rate tool from the Deal Analysis tools.
- 2.Enter the North hand, all 13 cards.
- 3.Enter the South hand, also 13 cards. East and West stay empty, because the tool deals them.
- 4.Pick the contract you want to test and the declarer, North or South.
- 5.Run it. The run costs 1 credit and plays the contract on 1,000 layouts.
- 6.Read the make percentage and the spread of tricks.
The percentage is the share of the 1,000 deals on which declarer took enough tricks. The spread shows how often each number of tricks came up. A contract that fails by one trick when it fails reads very differently from one that often goes two or three down.
How the figure is worked out
Your two hands stay fixed. Only the 26 cards you do not hold are shuffled between East and West. Each of the 1,000 layouts is then solved double dummy, with every player seeing every card, and a layout counts as a make when declarer's side takes enough tricks for the contract.
Two runs on the same hands can give slightly different figures, because each run draws new random layouts. Over 1,000 layouts, a difference of three or four points between two runs is normal, while a gap of twenty points between two contracts is real.
Double dummy play has a bias of its own. Declarer never misguesses a finesse, and the defenders never miss the best lead or the right switch. On hands where the real play turns on a guess, the figure shows what the cards allow, which is more than a player at the table can always find.
At IMPs, a vulnerable game needs to make about 37.5 percent of the time and a game not vulnerable about 45.5 percent. The game and slam odds guide gives the figures for slams and for matchpoints.
What it costs
Every run costs 1 credit, whatever the contract. New accounts get 7 starter credits once, enough for seven runs, and they are not refilled each month. Pro includes 20 credits a month for $7 a month or $60 a year, and Master 55 a month for $12 a month or $99 a year. Plan credits do not roll over.
Credit packs never expire and come as 20 credits for 3.50, 55 for 8.50 and 120 for 17.50, in dollars or euros depending on where you are. The plans are compared on the pricing page.
Limits
- The opponents' cards are dealt at random. The tool does not shape them to fit an auction, so after an overcall or a preempt the figure leaves out what the bidding showed.
- Both North and South must be complete hands. To test one hand opposite many possible partner hands, the Bridge Lab simulator can deal any seat from constraints.
- Each run tests the one contract you pick. The simulator compares up to five contracts on the same deals.
- The results are double dummy, with the bias described above.
Common questions
Short answers to what readers ask most.
- How often does 3NT make?
- It depends on the two hands, and the contract success rate tool measures it for any pair you enter. Pick 3NT and it reports the share of 1,000 random layouts on which nine tricks come in double dummy.
- What is a contract success rate in bridge?
- It is the percentage of possible deals on which a contract makes. BridgeTricks works it out by dealing the opponents' cards 1,000 random ways and solving each deal double dummy.
- How do I use contract odds to decide whether to bid game?
- Test the game on the two hands and compare its make percentage with what a game needs. At IMPs that is about 37.5 percent vulnerable and 45.5 percent not vulnerable. At matchpoints the break-even is roughly 50 percent.
- How is this different from a double dummy solver?
- A double dummy solver analyzes one fixed deal with all 52 cards known. The contract success rate tool keeps only your two hands fixed and plays the contract over 1,000 layouts of the other cards.
- Is it a bridge contract simulator?
- It is a small one. It runs a double dummy simulation of one contract on two fixed hands. For bigger studies, with constraints, up to 20,000 hands and up to five contracts compared, use the Bridge Lab simulator.
- Does the tool take the opponents' bidding into account?
- It does not. The opponents' 26 cards are dealt at random, so their bidding plays no part in the figure.
Open the contract success rate tool to test a contract. The double dummy solver guide covers single deals, and the hand simulator guide covers studies with constraints and several contracts.
Enter the North and South hands, pick a contract and see how often it makes over 1,000 layouts.
More tool guides
- The Double Dummy SolverHow the BridgeTricks double dummy solver works: makeable contracts for every declarer and strain, card-by-card play, and free manual entry with no account.
- The Bridge Hand SimulatorHow the Bridge Lab simulator works: up to 20,000 hands that fit your constraints, solved double dummy to compare contracts or rank every opening lead.