Counting Effective Tiles | Ukeire and Tile Efficiency
DocumentationCounting Effective Tiles | Ukeire and Tile Efficiency

Author: MJ Lab

Counting Effective Tiles

Last updated: 2026-06-18

Ukeire means tiles that lower shanten after your discard. Quantifying it makes tile efficiency comparisons objective—learn this right after shanten.

What Is Ukeire

  • Types — how many tile IDs help
  • Counts — tiles left in the wall (4 minus held)

More types and tiles at the same shanten usually mean faster wins.

How to Count

  1. Apply each candidate discard
  2. Try adding each of 34 tile types; note those that reduce shanten
  3. Sum remaining copies (typically 4 - in hand)

Same definition as calculateEffectiveTiles in this project.

Wide one-shanten

Shanten 1, 9 types / 23 tiles. Every man tile helps—very fast shape.

Narrower comparison

Also shanten 1 but only 7 types—weaker efficiency.

Comparing Discards

When shanten stays equal, prefer maximum ukeire unless scoring or safety overrides. At one-shanten see One-Shanten Discard.

Basics: Shanten · Overview: Tile Efficiency.

One-shanten training

Answer effective tiles for one-shanten hands—great for tile-count awareness.Open one-shanten training