Bridge Hand Generator: Deal Random Hands With Conditions

A bridge hand generator is a program that deals random bridge deals, either fully random or matching conditions you set, such as "South holds 15 to 17 points and a balanced hand". Players use generators to practice bidding, to prepare teaching hands, to test a convention on many deals, and to print hand records for club games.

The idea is simple: shuffle a virtual deck, give each seat 13 cards, and keep the deal only if it fits the conditions. What makes a generator useful is everything around that: the conditions you can express, the formats it saves to, and what you do with the hands afterward.

A random deal is one of a huge number of possible deals: there are 53,644,737,765,488,792,839,237,440,000 ways to deal 52 cards into four hands of 13, about 5.36 x 10^28. You will never see the same deal twice by chance.

A good generator uses a properly random shuffle, so every deal is equally likely. That matters more than it sounds: hand-shuffled decks are often not well mixed, and players notice more even suit splits than the true odds predict. Computer-dealt hands, as used in most clubs since dealing machines arrived, follow the real probabilities. You can check those probabilities in the bridge odds tables.

Most generators work the same way:

1. Choose the number of deals, from one board to several hundred.
2. Set the dealer and vulnerability, or let them follow the standard board numbering (board 1: North deals, nobody vulnerable).
3. Add conditions for any seats you care about. Leave the other seats random.
4. Generate. The program deals random hands and keeps only those that pass every condition.
5. Review or export the deals: on screen, as a file, or as a printable sheet.

The tighter your conditions, the more random deals the generator throws away. A balanced hand with 15 to 17 points comes up about once in 20 random hands (4.87%), so to find 100 such deals the program checks about 2,000. A rare shape, such as a 7-5 two-suiter (about one hand in 900), needs close to 100,000 tries for 100 deals. Good generators handle this in a second or two.

Conditions describe a hand in the same terms you use at the table:

A balanced condition only forces balanced hands. If you leave it off, the hand can be balanced or not; it does not mean "unbalanced". For an unbalanced hand you need an explicit "not balanced" condition. Mixing these up is the most common mistake when people write conditions.

Here is one deal from a generator set to: South 15-17 high card points and balanced; North 8-9 points. East and West are random.

South has 15 points with a 3-3-4-3 shape and North has 9 with a 3-4-2-4 shape, so both conditions pass. West received 12 points and East 4. In PBN notation the same deal reads:

N:A73.K962.J4.JT74 652.843.7652.A53 KQ4.AJ5.KT93.Q82 JT98.QT7.AQ8.K96

North's hand comes first, then the other seats clockwise: East, South, West. Each hand lists spades, hearts, diamonds and clubs, separated by dots, with T for the ten.

A 1NT opening and an invitational 2NT raise fit this deal. North has four hearts, so many pairs would start with Stayman, and South's 2♦ answer (no major) would lead to 2NT or 3NT.

PBN (Portable Bridge Notation) is the standard text format for bridge deals. A PBN file is a list of boards, each with tags such as [Board "1"], [Dealer "N"], [Vulnerable "None"] and [Deal "N:..."]. Almost every bridge program reads it, including scoring programs, dealing machines' software and hand-record printers. BridgeDummy's double dummy analyzer accepts a pasted PBN deal and shows how many tricks every contract makes.

LIN is the format used by Bridge Base Online. It packs a deal (and often the bidding and play) into one line of tags separated by bars. The md| tag holds the deal: a digit for the dealer (1 South, 2 West, 3 North, 4 East) followed by the hands in the order South, West, North, East, with suit letters before each suit. LIN is handy for loading deals into online tables or hand viewers.

PDF output is for people: a printable sheet with one diagram per board, often with the double dummy table under each one. Clubs hand these out after a session, and teachers use them for lesson handouts.

Some generators also write files for dealing machines, which sort physical cards into boards so a club can play the generated deals at real tables.

• Bidding practice with a partner. Generate 20 deals where one of you opens 1NT, bid them online or on paper, then compare with the full deal.
• Testing a convention. Before you add a convention, generate the hands it is meant for and see how often it helps. This is how most players decide whether a gadget is worth the memory.
• Teaching. Teachers set conditions so that every table gets the same lesson theme, such as a finesse in spades.
• Hand records. Clubs generate the session's deals in advance and print the records.
• Answering a "what if". Should you open this hand in third seat? Deal many hands that fit what the auction told you and count how often each choice works.

The last use is where a plain generator stops and a simulation starts. BridgeDummy's custom simulations let you describe the auction and the hand constraints, generate the matching deals, and compare contracts or leads by double dummy results over all of them. Instead of reading 200 deals yourself, you get the answer: which contract scores best on average and how often each lead beats the contract. Our guide on how to run bridge simulations walks through it, and double dummy analysis explains what the solver measures.

For the probabilities behind these conditions, see hand patterns and high card points.