Fu calculation in riichi mahjong, step by step

The fu checklist

Start at 20 fu, add, then round up to the next 10:

Closed hand won by ron: +10. Self-draw: +2.
Triplets: 2 (open simple), 4 (open 1/9/honor, or closed simple), 8 (closed 1/9/honor). Quads: four times that.
A pair of value tiles: +2.
A closed, edge or single-tile wait: +2.

You are in riichi and win by ron on . Build the fu.

Ron from across Riichi

Base fu

Open hands

No +10 for an open ron, and a triplet completed by ron counts as open. Open hands often land on 30.

You called pon on white dragons and win by ron on . Build the fu.

Ron from right

Base fu

Self-draw

A self-draw adds 2 fu, and a triplet you drew yourself counts as closed. (If the winning tile can be read more than one way, like with , the reading that scores most counts.)

You draw and win. Build the fu.

Tsumo

Base fu

Pinfu by self-draw

Pinfu by ron is 30 fu (20 + 10). By self-draw it is fixed at 20: the +2 is not added.

How many fu is pinfu won by self-draw?

Seven pairs

Seven pairs has its own fixed fu, never rounded.

How many fu is seven pairs?

A quick estimate

Most hands land on a few values: pinfu 30 by ron, seven pairs 25, an open hand about 30, any other closed hand about 40 by ron (30 by self-draw). Count exactly when the hand has a quad or a closed triplet of 1s, 9s or honors.

A closed hand with all simples wins by ron on a closed wait. What is it worth?

Ron from across