What are the Church Laws governing ingredients and shapes of altar bread in the Catholic Church? There appears to be perfect uniformity in the texture and make of the Sacramental Bread in Catholic churches all across the world. I wish to know if there are any laws governing the ingredients and method of preparation of the Sacramental Bread in the Roman Catholic Church? I also wish to know why the Holy Host administered to the faithful is perfectly round in shape whereas it could have been given the shape of `having been broken', say square, in order to avoid waste while it is  being cut from a larger bread.
Can.  924 §2. The bread must be only wheat and recently made so that there is no danger of spoiling.
[…]
Can.  926 According to the ancient tradition of the Latin Church, the priest is to use unleavened bread in the eucharistic celebration whenever he offers it.

Regarding the shape, canonist Dom Augustine, O.S.B., commentates on the 1917 Code Can. 815, the equivalent of 1983 Can.  924 quoted above:

As to the form of the bread, round hosts are used in the Latin Church, whereas the Oriental Church employs square hosts.9 The size of the host for Holy Mass and exposition in the Ostensorium should be from two to three and of the particles for distribution about one inch. The altar breads should be neither too thick nor too thin.10


Benedict XIV, Di Sac. Missæ, I, c. 6 [De Hoſtia, &quot;On the Host&quot;].

Prümmer, l. c. [Manuale Theologiæ Moralis], III, n. 171.



Also, round hosts are made with an iron, so there is no &quot;waste while it is being cut from a larger bread&quot;. This baking machine makes hosts and particles: