The omer (Hebrew: עֹ֫מֶר ‘ōmer) is an ancient Israelite unit of dry measure used in the era of the Temple in Jerusalem. It is used in the Bible as an ancient unit of volume for grains and dry commodities, and the Torah mentions as being equal to one tenth of an ephah. According to the Jewish Encyclopedia (1906), an ephah was defined as being 72 logs, and the Log was equal to the Sumerian mina, which was itself defined as one sixtieth of a maris; the omer was thus equal to about 12⁄100 of a maris. The maris was defined as being the quantity of water equal in weight to a light royal talent, and was thus equal to about 30.3 litres, making the omer equal to about 3.64 litres. The Jewish Study Bible (2014), however, places the omer at about 2.3 liters.
In traditional Jewish standards of measurement, the omer was equivalent to the capacity of 43.2 eggs, or what is also known as one-tenth of an ephah (three seahs). In dry weight, the omer weighed between 1.560 kg. to 1.770 kg., being the quantity of flour required to separate therefrom the dough offering.
The word omer is sometimes translated as sheaf — specifically, an amount of grain large enough to require bundling. The biblical episode of the manna describes God as instructing the Israelites to collect an omer for each person in your tent, implying that each person could eat an omer of manna a day. In the Instructions of Moses (Torah in Hebrew), the main significance of the omer is the traditional offering of an omer of barley on the day after the Sabbath, or according to the pharisian and rabbinical view, on the second day of Passover during the feast of unleavened bread (during the period of Temple sacrifice) as well as the tradition of the Counting of the Omer (sefirat ha'omer) - the 49 days between this sacrifice and the two loaves of wheat offered on the holiday of Shavuot.
Jews in Lancaster, Pennsylvania used an omer board from about 1800 to keep track of harvest days between Passover and Pentecost. An example of such a board survives at the Herbert D. Katz Center for Advanced Judaic Studies at the University of Pennsylvania.
The omer should not be confused with the homer, a much larger unit of volume for liquids.
- Exodus 16:36
- "Weights and Measures", Jewish Encyclopedia (1906)
- there were two types of talent - royal and common, and each type came in a light form and a heavy form, with the heavy form being exactly twice the weight of the light form
- Adele Berlin; Marc Zvi Brettler (17 October 2014). The Jewish Study Bible: Second Edition. Oxford University Press. p. 381. ISBN 978-0-19-939387-9.
- Based on the Aramaic Targum of pseudo-Jonathan ben Uzziel on Exodus 16:36 who says: "an omer is one-tenth of three seahs." In Hebrew measures, 1 seah is equal to the capacity of 144 eggs. Three seahs are the equivalent of 432 eggs; one-tenth of this is 43.2 eggs (The Mishnah, ed. Herbert Danby, Oxford University Press: Oxford 1977, Appendix II, p. 798)
- Maimonides brings down its approximate weight in Egyptian dirhams, writing in Mishnah Eduyot 1:2: "...And I found the rate of the dough-portion in that measurement to be approximately five-hundred and twenty dirhams of wheat flour, while all these dirhams are the Egyptian [dirham]." This view is repeated by Maran's Shulhan Arukh (Hil. Hallah, Yoreh Deah § 324:3) in the name of the Tur. In Maimonides' commentary of the Mishnah (Eduyot 1:2, note 18), Rabbi Yosef Qafih explains that the weight of each Egyptian dirham was approximately 3.333 grams, which total weight of flour requiring the separation of the dough-portion comes to appx. 1 kilo and 733 grams. Rabbi Ovadiah Yosef, in his Sefer Halikhot ʿOlam (vol. 1, pp. 288-291), makes use of a different standard for the Egyptian dirham, saying that it weighed appx. 3.0 grams, meaning the minimum requirement for separating the priest's portion is 1 kilo and 560 grams. Others (e.g. Rabbi Avraham Chaim Naeh) say the Egyptian dirham weighed appx. 3.205 grams, which total weight for the requirement of separating the dough-portion comes to 1 kilo and 666 grams. Rabbi Shelomo Qorah (Chief Rabbi of Bnei Barak) brings down the traditional weight used in Yemen for each dirham, saying that it weighed 3.36 grams, making the total weight for the required separation of the dough-portion to be 1 kilo and 770.72 grams.
- Kiron, Arthur (2000). The Professionalization of Wisdom: The Legacy of Dropsie College and Its Library, in Michael Ryan and Dennis Hyde, eds., The Penn Libraries Collections at 250. Philadelphia: University of Pennsylvania Library. p. 182.