The mitzvot of the Seder require that Matzah and Maror be “eaten” in appropriate quantities and not just nibbled. The minimum requirement for eating a food is a “Czayit” (=size of an olive). This must be eaten preferably within 4 minutes but if necessary in up to 7 minutes. A “Czayit” is approximately the size of 1 fluid oz or 29 cubic centimeters of water. The weight of 29cm3 of water is 29grams. Therefore most of the guides (including previous editions of the Kashrut Authority Pesach Handbook) state that a “Czayit” of matzah is 1oz or 29grams of matzah. According to most opinions this is incorrect.
In general all Torah measurements are established by volume rather than by weight. Therefore one “Czayit” of matzah is equivalent to the amount of matzah that takes up the ‘volume’ of 29 grams of water or 29ml. In reality the ratio of volume to weight of matzah compared to water is no more than 2/3. This means that the Shiur of a “Czayit” for the fulfillment of biblical mitzvot is approximately 19 grams of matzah, (not 29 grams) which is approximately 1/3 of a hand made shmurah matzah or 2/3 of a machine matzah. This amount is considerably less than the usually recommended amounts.
Furthermore, the requirement for a “Czayit” for a Rabbinic Mitzvah is only 2/3 the above measure. Therefore a “Rabbinic Czayit” is only 13 grams of matzah.
Therefore for Korach (the sandwich) all that is required is one rabbinic “Czayit” a quarter of a Shmurah Matzah or half a machine matzah. When eating the customary two “Czaytim” for Afikoman all that is required to be eaten is 26 grams of matzah (2 rabbinic “Czaytim”) i.e; 1/2 a shmurah matzah or 1 machine matzah. Similar measurements apply to maror.
The above information allows us to ascertain the appropriate
requirements of matzah and marror with realistic amounts, able to be consumed relatively easily by all the seder participants.