SECTION 486 The Laws Pertaining to the Measure of a Kezayis (1-2)

סימן תפו דִּין שִׁעוּר כְּזַיִת וּבוֹ ב' סְעִיפִים:

1 [The term] kezayis, [translated as “an olive-sized portion,”] that is universally used [refers to an olive] that is neither small, nor large, but of average size.1 This type of olive is called agori, i.e., [an olive] whose oil is collected or stored within it.2

[There is a difference of opinion among the Ri­shonim regarding] the size of this measure. Some authorities maintain that it is half the size of an egg.3 Others maintain that [a kezayis] is slightly less than a third [of the size of an egg. These authorities arrive at this conclusion] according to the explanations in sec. 368[:3], that the [volume of] food comprising the two meals [that are required] for an eruv is eighteen dried figs, which constitute six eggs. Thus, a dried fig is a third of an egg. [Now,] an olive is [slightly] smaller than a dried fig.4 [This leads to the conclusion that the size of an olive is slightly less than a third of an egg. By contrast,] according to the first opinion, the [volume of the] eighteen figs comprising the two meals [that are required] for an eruv constitute more than 18 half-eggs.5

It was already explained in sec. 368[:3]6 and sec. 409,7 that fundamentally, [the halachah] follows the authorities who maintain that [a volume of food] larger than six eggs is not necessary for an eruv. [The rationale is that establishing] an eruv is a Rabbinic ordinance, and therefore, the lenient perspective may be followed. Similarly, with regard to maror8 and every other ordinance instituted by the Sages where the measure [used] is an olive-sized portion, one may rely on the authorities who maintain that [an olive-sized portion] is slightly less than a third of an egg. However, with regard to [the mitzvah of eating] matzah, which is a Scriptural commandment,9 and similarly with regard to all other Scriptural obligations, one should rule stringently and follow the first opinion.

[A different rule applies] with regard to the blessings recited after eating and the Grace after Meals, [in which instance,] the measure [a person must eat to be required to recite these blessings] is an olive-sized portion:10 [In that instance, we follow the principle:] When there is a question [as to] whether [or not] a blessing [is required], a lenient ruling is rendered,11 and the blessing is not recited unless one eats [the measure of] half an egg. [However,] initially, [a person] should be careful not to place himself in a situation where there is a question [regarding] whether a blessing [is required. To prevent this,] he should [either] eat [an amount equal to] half an egg[-sized measure] or [eat] much less than a third of an egg[-sized measure], in an instance when he is not required [to eat] an olive-sized portion.

Similarly, care must be taken with regard to all other matters in which measuring [an olive-sized portion according to] the larger measure12 would constitute a leniency and [measuring it according to] the smaller measure would constitute a stringency, for example, the obliteration of chametz.13 See sec. 442:[27-30] and sec. 444[:19].14

א כְּזַיִת הָאָמוּרא בְּכָל מָקוֹםב – אֵינוֹ לֹא קָטָן וְלֹא גָּדוֹל, אֶלָּא בֵּינוֹנִי,1 וְזֶה זַיִת הַנִּקְרָא "אֲגוּרִי",ג שֶׁשַּׁמְנוֹ אָגוּר בְּתוֹכוֹ.ד,2

וְשִׁעוּרוֹ – יֵשׁ אוֹמְרִיםה שֶׁהוּא כַּחֲצִי בֵּיצָה.3 וְיֵשׁ אוֹמְרִיםו שֶׁהוּא פָּחוֹת מְעַט מִשְּׁלִישׁ, לְפִי מַה שֶּׁנִּתְבָּאֵר בְּסִימָן שס"חז שֶׁמְּזוֹן שְׁתֵּי סְעוּדוֹת שֶׁל עֵרוּב שֶׁהוּא י"ח גְּרוֹגָרוֹת יֵשׁ בָּהֶן כְּשִׁשָּׁה בֵּיצִים, אִם כֵּן הַגְּרוֹגֶרֶת הוּא שְׁלִישׁ בֵּיצָה, וְהַזַּיִת הוּא קָטָן מֵהַגְּרוֹגֶרֶת.ח,4 וּלְפִי סְבָרָא הָרִאשׁוֹנָה, הַי"ח גְּרוֹגָרוֹת שֶׁל שְׁנֵי סְעוּדוֹת שֶׁל עֵרוּב הוּא יוֹתֵר מִי"ח חֲצָאֵי בֵּיצָה.ט,5

וּכְבָר נִתְבָּאֵר בְּסִימָן שס"חי,6 וְת"טיא,7 שֶׁהָעִקָּר כְּהָאוֹמְרִים שֶׁאֵין צָרִיךְ יוֹתֵר מִכְּשִׁשָּׁה בֵּיצִים לְעֵרוּב, לְפִי שֶׁהָעֵרוּב הוּא מִדִּבְרֵי סוֹפְרִים וְהוֹלְכִין בּוֹ לְהָקֵל. וְאִם כֵּן בְּמָרוֹר8 שֶׁהוּא מִדִּבְרֵי סוֹפְרִים, וְכֵן כָּל דָּבָר שֶׁהוּא מִדִּבְרֵי סוֹפְרִים שֶׁשִּׁעוּרוֹ בִּכְזַיִת – יֵשׁ לִסְמֹךְ עַל הָאוֹמְרִים שֶׁהוּא פָּחוֹת מְעַט מִשְּׁלִישׁ בֵּיצָה.יב

אֲבָל בְּמַצָּה שֶׁהִיא מִן הַתּוֹרָה,יג,9 וְכֵן כָּל דָּבָר שֶׁהוּא מִן הַתּוֹרָה – יֵשׁ לְהַחֲמִיר כַּסְּבָרָא הָרִאשׁוֹנָה.

אֲבָל לְעִנְיַן בְּרָכָה אַחֲרוֹנָה וּבִרְכַּת הַמָּזוֹן שֶׁשִּׁעוּרוֹ בִּכְזַיִתיד,10 – סְפֵק בְּרָכוֹת לְהָקֵל,טו,11 וְלֹא יְבָרֵךְ עַד שֶׁיֹּאכַל כַּחֲצִי בֵּיצָה.12

וּלְכַתְּחִלָּה יֵשׁ לִזָּהֵר שֶׁלֹּא לְהַכְנִיס עַצְמוֹ לִידֵי סְפֵק בְּרָכָה, וְיֹאכַל כַּחֲצִי בֵּיצָה אוֹ הַרְבֵּה פָּחוֹת מִשְּׁלִישׁ בֵּיצָה בְּדָבָר שֶׁאֵין צָרִיךְ כְּזַיִת.טז

וְכֵן צָרִיךְ לִזָּהֵר לְדַקְדֵּקיז בִּשְׁאָר דָּבָר שֶׁשִּׁעוּר גָּדוֹל12 הוּא קֻלָּא וְשִׁעוּר קָטָן הוּא חֻמְרָא,יח כְּגוֹן בִּעוּר חָמֵץ,13 עַיֵּן סִימָן תמ"ביט וְתמ"ד:כ,14

2 One must be careful when measuring the olive-sized portion of the vegetables with which he intends to fulfill the obligation of maror, and crush [them so that there is no] air between the leaves. Thus, the olive-sized portion [that he will be measuring] will include [just] the vegetables themselves and not the air between [the leaves].

Similarly, if there is empty space in the matzah, the empty space is not included in [the volume of] the olive-sized portion, and it must be crushed.15 (However, if there is no empty space in a matzah, even if it is soft and sponge-like, it need not be crushed [when measuring the olive-sized portion].)16

ב צָרִיךְ לִזָּהֵר כְּשֶׁמְּשַׁעֵר כְּזַיִת בִּירָקוֹת שֶׁיּוֹצֵא בָּהֶם יְדֵי חוֹבַת מָרוֹר, שֶׁיְּמַעֵךְ הָאֲוִיר שֶׁבֵּין עֲלֵי הַיְרָקוֹת וִישַׁעֵר שִׁעוּר כְּזַיִת בַּיְרָקוֹת עַצְמָם וְלֹא בָּאֲוִיר שֶׁבֵּינֵיהֶם.כא וְכֵן אִם יֵשׁ חָלָל בַּמַּצָּה – אֵין הֶחָלָל מִצְטָרֵף לִכְזַיִת,כב וְצָרִיךְ לְמַעֲכוֹ.כג,15

(אֲבָל אִם אֵין חָלָל בַּמַּצָּה, אֲפִלּוּ הִיא רַכָּה וַעֲשׂוּיָה כִּסְפוֹג – אֵין צָרִיךְ לְמַעֲכוֹכד):16