Helek

The helek (Hebrew חלק, meaning "portion", plural halakim חלקים) is a unit of time used in the calculation of the Hebrew calendar. Other spellings used are chelak and chelek, both with plural chalakim.

The hour is divided into 1080 halakim. A helek is 3⅓ seconds or ¹/₁₈ minute. The helek derives from a small Babylonian time period called a she, meaning '"barleycorn", itself equal to ¹/₇₂ of a Babylonian time degree (1° of celestial rotation).

360 degrees x 72 shes per degree / 24 hours = 1080 shes per hour.

The Hebrew calendar defines its mean month to be exactly equal to 29 days 12 hours and 793 halakim, which is 29 days 12 hours 44 minutes and 3⅓ seconds. It defines its mean year as exactly 235/19 times this amount.