Kiddush – How Much Wine
I own two very nice Kiddush cups – I believe both were wedding presents. One happens to be quite large and the other fairly small. Is there a minimum or maximum size a cup must be? Also, when I use the large one, I tend to take only a few sips after Kiddush and leave most of its contents for the meal. Do I have to drink the entire cup? (I wouldn’t last very long in the meal if I did.) :-)
The Aish Rabbi Replies:
There is no maximum size for a Kiddush cup. The minimum size is clearly stated. A Kiddush cup must hold what’s known as a revi'it (literally, “a quarter”) – 1/4 of a “log” (Shulchan Aruch 472:9). How big is a revi'it? The Talmud (Pesachim 109a) measures it in terms of thumb widths – as the equivalent of a cube of dimensions 2x2x2.7 “fingers.” Elsewhere a log is defined as the volume of 6 eggs, making a revi'it 1.5 eggs.
Needless to say, there is much discussion in the more recent commentators exactly what these measurements mean in modern units. They note in particular that the two measures hardly square: Either our thumbs are somewhat larger than they were in Talmudic times or our eggs are smaller. (The former is actually much more likely.) As a result, opinions vary drastically – anywhere from less than 3 to over 5 ounces.
What should one do practically? There is another relevant distinction. On Friday night there is a Torah obligation to recite Kiddush, based on the verse “Remember the Sabbath day to sanctify it” (Exodus 20:8). By contrast, the Kiddush of Shabbat day is a rabbinical obligation – as a way of lending importance to the meal. Thus, for the Friday night Torah obligation, one should be more meticulous and use a larger measure. Most opinions measure this at 4.42 ounces (130.7 ml). On Shabbat day 3 ounces (88.7 ml) is sufficient (Kol Dodi Haggadah, in name of Rabbi Moshe Feinstein).
Now how much of the cup should you drink? That is actually a separate question which I dealt with recently. Please see here for the response.
I should also mention that the cup should be filled completely even if it holds much more than the prescribed amount and more than you intend to drink (Rema 183:2).