The amount of dirt you need to get some peace is a two mat area. Two tatami mats, that is. This is a pretty common measurement in Japan, so you should get really familiar with the amount of space that two tatami mats take up together.
A two mat area also happens to be big enough to hold two bodies (つぼ). That's enough space to bring peace to two living, or dead, bodies!
Currently there are no similar looking kanji which exist in the WaniKani learning system