Pinfu is a standard yaku. This yaku is defined by having 0 fu aside from the base 20 fu, or 30 fu in the case of a closed ron. It is worth 1 han and closed only.
In English, pinfu is sometimes referred to as "all sequences". However, the yaku is not as simple as that. Other than having an open hand, it is possible for a hand to be composed of all sequences and still not be classed as a pinfu.
To understand pinfu, players must understand the nature of fu. Fu are a set of points associated with hand composition. Pinfu lacks any fu except the 10 menzen-kafu for winning with a closed ron.
- Any koutsu or kantsu is worth at least 2 fu. A pinfu hand must have four shuntsu.
- Winning from a tanki, kanchan, or penchan wait is worth 2 fu. A pinfu hand must win from a ryanmen wait, i.e., the final tile must complete a shuntsu that was completable on any side.
- An open hand worth 20 fu is counted as 30 fu. Pinfu may only be awarded to a closed hand.
A winning tile drawn from the wall is normally worth 2 fu. If the closed hand otherwise qualifies as pinfu, these 2 fu are waived. The hand is then scored at 20 fu and at least 2 han for [Menzen tsumo|menzen tsumo] and pinfu. Some rule variations may not allow waiving these fu and score such a hand as 30 fu, tsumo, without pinfu. Such variations are rare.