plural kittel, in Judaism, a white robe worn in the synagogue on such major festivals as Rosh Hashana and Yom Kippur. The rabbi wears it, as does the cantor, the blower of the Shofar (ritual ram's horn), and male members of Ashkenazi (German-rite) congregations. Before a Seder dinner, the leader of the Passover (Pesach) service dons a kittel, and in Orthodox communities the bridegroom wears it…
A kittel (Yiddish: קיטל;, robe) is a white robe worn on special occasions by religious Jews. According to many traditions a groom wears a Kittel for the first time on his wedding day. It is worn on Rosh Hashanah and Yom Kippur, in keeping with the Biblical "our sins shall be made as white as snow" (Isaiah 1:18). Many Jews also wear a Kittel when leading the Passover Seder. The cantor also wears it during a few special services during the year, such as the first night of Selichot, the seventh day of the Holiday of Sukkot (also known as Hoshanah Rabbah), the Musaf prayers of Shemini Atzeret and the first day of Passover, where the prayers for rain (Tefilat HaGeshem) and dew (Tefilat HaTal) are respectively recited.
The white color is said to symbolize purity, which partly explains its use during weddings. It is also felt to signify unity with the bride (who also wears white) and the beginning of a new life together.
In addition to this usage, the dead are also buried in a kittel, providing simple dress that assures equality for all in death.
The size is determined by the following chart:
| Suit Size | Kittel Size |
|---|---|
| This chart works together with the length chart. | |
| 34 or less | Small |
| 36-42 | Medium |
| 42-48 | Large |
| 50 | X-Large |
| 52 | X-Large |
| 54 | XX-Large |
The length is determined by the following chart:
| Suit Length | Kittel Length |
|---|---|
| This chart works together with the size chart. | |
| Short | 46" |
| regular/Medium | 48" |
| Long | 50" |
| X-Long | 52" |
The size is determined by the size chart. However, you may want to take into consideration that jacket factor.
Most people wear a jacket, Beketche, or tuxedo underneath the Kittel, during the Chuppah. This makes the shoulder-width larger. You also would consider that a jacket is usually used together with the Kittel only under the Chuppah, not later on (i.e. Passover, Yom Kippur, etc.), so you would moderate to accommodate both fits.
Indeed, it is customary in Ashkenazi communities for the groom to wear a kittel during the Chupah ceremony.1 There are several reasons for this custom, the following are two of them:

