913. Measures of Volume

Eiruvin 1:13

The Rambam explains the measures of volume used in halacha 1:11:

A seah is equal to six kav; a kav is four log; a log is four reviis. A reviis was defined in the previous halacha. It is important for a person to commit these measurements to memory.

Eiruvin 1:14

Any food that may be eaten can be used for an eiruv or a shittuf even if the individual using it is not personally permitted to eat it. Accordingly, a nazir (nazirite, who may not eat grape products) may make a shittuf using wine, and a non-kohein may do so using terumah (which may only be eaten by kohanim). Similarly, if a person makes a vow or an oath not to eat a particular type of food, he may still use it to make an eiruv or a shittuf. The underlying rationale is that the item is fit to be eaten, even if not by him.