Can K’Zayit be Defined by Calories?

Question

I have a question related to the k’zayit according the Halacha. I have read the correct amount of matzah to eat during Pesach is equivalent to “the size of an olive”. However, the Rambam and other rabbis are very contradictory or ambiguous when it comes to defining the size of an olive; they often do it in terms of the size of an egg, which is equally difficult to measure or standardize. Some try to do this by agreeing it is the volume, not the weight of the olive that matters.

My question is: Can the “size of an olive” be defined in terms of calories (thus eating the same calories of matzah as the calories found in an olive) or is that also incorrect? I think that calories are an equivalent unit for comparing food these days, more accurate than weight or volume, but I might be wrong. Thank you for answering my question!

Eric

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Answers

  1. The Just Ask! - AskTheRabbi.org Team

    As you write, it is all a little confusing! A Halachic K’Zayit is actually the size of an egg nowadays because in Talmudic times an olive was much larger than it is today. However, in any event, a K’Zayit is measured according to volume and not according to size. The denser something is, the smaller it needs to be in volume to reach a K’Zayit. Matzah is actually a good example, as Matzah is very dense, and a K’Zayit for a hand Matzah is normally slightly less than half of a standard sized hand-Matzah.

    According to all Halachic opinions, the caloric count has no bearing whatsoever on measuring how much a K’Zayit is.

    Best wishes from the AskTheRabbi.org Team