Bridge odds: a cheat sheet
The chances worth knowing when you declare: how the opponents' cards in a suit split, and how often the common plays work.
These are the odds before the bidding and play tell you anything. Once they do, the odds change: a player who opened the bidding is likelier to hold the missing honors, and one who shows out of a suit holds none of it. The app's own odds at a guess take what you know into account (How it works).
How a suit splits
The cards you're missing in a suit, and how they're divided between the opponents, either way round.
| Missing | Splits |
|---|---|
| 2 | 1-1 52.0%2-0 48.0% |
| 3 | 2-1 78.0%3-0 22.0% |
| 4 | 3-1 49.7%2-2 40.7%4-0 9.6% |
| 5 | 3-2 67.8%4-1 28.3%5-0 3.9% |
| 6 | 4-2 48.4%3-3 35.5%5-1 14.5%6-0 1.5% |
| 7 | 4-3 62.2%5-2 30.5%6-1 6.8%7-0 0.5% |
| 8 | 5-3 47.1%4-4 32.7%6-2 17.1%7-1 2.9%8-0 0.2% |
An odd number of missing cards tends to split as evenly as it can (5 missing: 3-2, 67.8%). An even number, four or more, tends not to (6 missing: 4-2, 48.4%, against 3-3, 35.5%).
One card, or two
- A finesse for one missing card works when that card is with the right opponent: 50.0%.
- Two missing cards (say the king and the jack) are with the same opponent 48.0% of the time, 24.0% each way, and split 52.0%.
- So two finesses, where you need only one of them to work, succeed 76.0% of the time, and both work 24.0%.
Finesse or drop
North holds the honors and you lead toward them from South, so West is the player a finesse works against. The better play is in bold.
Eight cards, missing the queen
- 50.9% Cash the ace (in case the queen is singleton), then finesse
- 32.8% Cash the ace and king, hoping the queen falls (finessing instead if East shows out on the ace)
Nine cards, missing the queen
- 57.9% Cash the ace and king, hoping the queen falls (finessing instead if East shows out on the ace)
- 56.2% Cash the ace (in case the queen is singleton), then finesse
Ten cards, missing the king
- 50.0% Finesse, keeping the ace to take the king when West plays it
- 26.0% Cash the ace first, then finesse
Eleven cards, missing the king
- 52.0% Cash the ace, hoping the king falls
- 50.0% Finesse
A-Q-10 opposite three small, for two tricks
- 76.0% Finesse twice: the 10, then the queen (or the queen, then the 10)
- 54.8% Finesse the queen, then cash the ace
Eight ever, nine never: with eight cards missing the queen, finesse (50.9% against 32.8%); with nine, play for the drop (57.9% against 56.2%). Missing the king, finesse with ten cards and play for the drop with eleven.
Where these numbers come from
The app works out every number here itself. For how a suit splits, it counts every way the opponents' cards could be dealt. For a play like a finesse, it tries the play against every possible layout of the missing cards and adds up how often it works. The play numbers assume the opponents play sensibly, and that you can reach whichever hand you need to lead from.
If something looks wrong, .