One sa' is the traditional amount of staple food commonly used to measure zakat al-fitr per person. Zakat al-fitr is charitable giving connected with the completion of Ramadan and is generally distributed before the Eid al-Fitr prayer.
Classical Islamic sources describe the payment as a sa' of food, such as dates, barley, raisins, or another local staple. A sa' is an ancient volume measure, so its modern weight varies according to the food and the conversion method used.
Many contemporary Muslim communities calculate an equivalent cash amount instead. The exact monetary value therefore differs by country, staple food, and year. This measure should not be confused with ordinary zakat on wealth, which has different rules and calculation methods.