Now an omer is the tenth part of an ephah.

When he has leveled its surface, doesn't he plant the dill, and scatter the cumin seed, and put in the wheat in rows, the barley in the appointed place, and emmer as its borders?

The ephah and the bath are to be of equal volume; that is, the bath is to contain one tenth of an omer and the ephah one tenth of an omer. The omer is to be the standard on which their volume measurement is to be based.