Kuji Odds Calculator Guide

What kuji is and what you enter

Kuji is a blind-draw way of selling merch. A box holds a fixed number of tickets, and each draw gives you a prize such as Prize A or Prize B. A ticket that's been drawn leaves the box.

That means the odds change as the box empties. This calculator takes the tickets left per prize, the numbers shops post, and counts that in.

At minimum enter a prize name, the tickets left and tick the prize you want. Ticket price, prize values, the Last One value and how many you'll draw depend on what you want to see.

How the chance is counted

Call the tickets left N, your prize tickets K and your draws n. The chance of getting none is C(N-K, n) / C(N, n). The chance of at least one is 1 minus that.

Example: 80 tickets, 2 are Prize A, you draw 10. None shows up with probability (70 x 69) / (80 x 79), about 76.4%. So at least one is 149/632, about 23.6%.

The draws needed for 50% and 90% are found the same way, adding one draw at a time. Here that's 24 and 55. Draw 79 and only 78 tickets are not your prize, so one has to show up. That's 100%.

Expected draws and cost

The average number of draws until your first hit is (N + 1) / (K + 1). In the example that's 81 / 3, or 27.

Enter a ticket price and the calculator multiplies it by that to show the expected cost. It's an average over many people, so your own run can be quicker or slower.

Value per draw and buying it all

Expected value per draw is the sum of (tickets left x value) divided by the tickets left. It sits next to the ticket price so you can compare. Prizes with no value count as 0, and the screen says how many.

Buying it all shows the ticket price times the tickets left, next to the total value of what's left plus the Last One prize. The Last One prize goes to whoever draws the final ticket.

This app never tells you to buy or not to buy. It puts two numbers side by side, and every value is one you entered.

When it may not fit

The tickets left is your input, so a wrong count gives a wrong result. If you're unsure, ask the shop. The calculation assumes a well-mixed box where every ticket is equally likely.

The app doesn't fill in prize names or values. Values differ by product, and a wrong one would be false. Odds are not a guarantee.

Saving and sharing links

What you enter is saved in this browser only and never sent to a server. If browser storage is blocked, saving is skipped and the math still works.

Copy link puts the box numbers in the address. Whoever opens it sees the same box. The address has no names, accounts or other personal data.