Drawing tiles from the wall is drawing without replacement, so the calculator uses the hypergeometric formula: the number of ways to draw what you need divided by the number of ways to draw any tiles from the unseen pile.

Tiles in other players’ racks are as hidden from you as tiles in the wall, so from where you sit every unseen tile is equally likely to be your next draw. Use all 152 tiles minus the ones you have seen.

No. It only covers tiles you draw from the wall. A discard that gives you a call is an extra chance, so the real chance of getting a tile is a little higher.

Each Bam, Crak, Dot, wind and dragon has 4 copies. There are 8 Jokers and 8 flowers. Subtract the copies you have seen on your rack, in the discards and in exposed groups, or use the Tile Tracker to count them.

Set “How many do you need?” to 2. The calculator then gives the chance of drawing at least two of the matching tiles in your draws.

Add together the copies left of each tile that would help, and enter that total. The calculator treats them as one group of matching tiles.

No. Completing a hand depends on every tile the hand needs, and this tool does not use the NMJL card. Use it for each tile you are waiting on, as a guide to which tiles are worth chasing.

Check your table’s rules first. Many in-person tables do not allow phones during play, and online platforms often do not allow outside tools. It is best for practice and for reviewing a game afterwards.