A win is worth the sum of every pattern it matches, counted in tai (台). Miss one and you collect less than the hand earned; claim one that isn't there and the table will catch it. Seeing patterns quickly also changes how you play, because a hand that is one tile from 混一色 is worth steering there.
How to do it
1.
Start with how the hand is held: if nothing was claimed with 吃, 碰 or an exposed 槓, it is concealed (門清).
2.
Then how it won and what sits beside it: drawn yourself (自摸) or taken from a discard, and whether you hold any flowers. Holding none at all is 無花.
3.
Look at suits and honors: one suit only is 清一色, one suit plus winds and dragons is 混一色, honors only is 字一色, and all five kinds (characters, dots, bamboo, a wind, a dragon) is 五門齊. A triplet of 中, 發 or 白 scores on its own; a wind triplet scores when it is your seat wind or the round wind.
4.
Look at the shape of the sets: all runs with a numbered pair is 平胡, all triplets is 碰碰胡, and three, four or five triplets you formed yourself are 三暗刻, 四暗刻 or 五暗刻.
5.
Finish with the special patterns, such as dragon and wind combinations (小三元, 大四喜) and timing wins (槓上開花, 海底撈月). Every pattern that fits counts, so add them all.
With the winning 8索 next to 6-7索, all five sets are runs: 1-2-3 and 4-5-6 of characters, 7-8-9 of dots, 2-3-4 and 6-7-8 of bamboo. The pair is 5索, a numbered tile, so the hand is 平胡. Nothing was claimed, so add 門清, and with no flowers add 無花; it won on a discard, so there is no 自摸. Under the app's default rules that is 2 + 1 + 1 = 4 tai.
混一色: one suit plus honors
Concealed Hand · 1 tai
Half Flush · 4 tai
Red Dragon · 1 tai
No Flowers · 1 tai
Every numbered tile is bamboo and the rest are East (東) and red dragon (中), so the hand is 混一色, 4 tai. The winning 中 turns the pair of 中 into a triplet, which scores 紅中 for 1 tai. The two East winds are only the pair, so they score nothing even in an East round: only a triplet counts. Add 門清 and 無花 for 4 + 1 + 1 + 1 = 7 tai.
碰碰胡: five triplets
Self-draw · 1 tai
Concealed Hand · 1 tai
All Pungs · 4 tai
Five Concealed Pungs · 8 tai
Five Categories · 1 tai
Green Dragon · 1 tai
No Flowers · 1 tai
There are no runs: 1萬, 9筒, 5索, 7索 and the self-drawn green dragon (發) are all triplets, with a pair of South wind (南), so the hand is 碰碰胡, 4 tai. The win is drawn yourself, so 自摸 adds 1, and every triplet was formed in your own hand, so all five are concealed: 五暗刻, 8 tai. Characters, dots, bamboo, a wind and a dragon all appear, so 五門齊 adds 1; the 發 triplet adds 1 (青發); 門清 and 無花 add 1 each, for 17 tai.
Common mistakes
• Stopping at the biggest pattern. Every pattern that fits counts, so 混一色 with a 中 triplet is 混一色 plus 紅中.
• Calling a hand 平胡 when its pair is a wind or a dragon, or when one of its sets is a triplet.
• Scoring a pair as if it were a triplet. A pair of 中 or of your seat wind is worth nothing; only a triplet or kong scores.
• Forgetting the small ones. 門清, 無花 and 自摸 are 1 tai each and are the patterns players drop most often.
Practice now
Below is the app's pattern drill at Novice (入門), the free tier: ten winning hands, and you pick every pattern each one scores. The hands and their scoring come from the real game engine, under the app's default rules.
A tai is the unit a winning hand is counted in. Every pattern the hand matches adds its tai, and the winner collects the table's base plus the total tai times the value of one tai.
How is 16-tile Taiwanese scoring different from 13-tile mahjong?
A 16-tile hand needs five sets and a pair, one set more than the 13-tile game, and it is scored in tai rather than fan. Flowers count directly: a flower matching your seat is worth tai, and holding none at all scores 無花. Patterns that need five sets, like 五暗刻, only exist in the 16-tile game.
Is every pattern worth the same tai at every table?
No. The pattern names are standard, but how many tai each is worth is often a house rule (家規). These examples use the app's default rules, which you can change in the app; that is why the drill asks for patterns, not a total.
Does winning on a discard change which patterns count?
Yes. 自摸 is itself worth 1 tai, and some patterns need one way of winning: 全求人 is only a win on a discard, and 槓上開花 is only a self-drawn win on the replacement tile after a kong.