Move the slider to show a sublist of ten shapes in order of probability.

For the shapes displayed, the calculator produces the probabilities, which are expressed as per cent.

What are your chances that your longest suit is exactly four cards? Look up the 4-4-4-1, 4-3-3-3, 4-4-3-2 holdings and figure 2.993 + 10.54 + 21.55 to find that happens 35% of the time. What about 5 cards maximum? Happens 44% of the time, which is more often than 4 cards maximum.

What are your chances that your hand is balanced? Look up the 5-3-3-2, 4-3-3-3, 4-4-3-2 holdings and figure 15.52 + 10.54 + 21.55 to find that happens 47.6% of the time. The semi-balanced shapes (7-2-2-2, 6-3-2-2, 5-4-2-2) occur about 16.7% of the chances.

Try a few yourself! What does this mean for your bidding system?