Is a yahrzeit kept by the Hebrew or the English date?

The Hebrew date

The Jewish calendar governs all religious observances, and the yahrzeit follows it. Since Hebrew dates move against the civil calendar, the yahrzeit falls on a different civil day each year; our Jewish calendar can show it.

Special cases

If someone died in Adar of a regular year, in a leap year (with two Adars) Ashkenazim generally keep it in the first Adar, some in both; Sephardim keep it in the second. If the burial was more than three days after death, the first yahrzeit is kept by the day of burial according to some authorities, and thereafter by the day of death.

Customs

A candle burns for 24 hours from the evening. The son (or another relative) says Kaddish, leads services if he can and may be called to the Torah on the Shabbat before. Many fast or study Mishnah in memory of the deceased.

Finding the date

If the death occurred after nightfall, the Hebrew date is already that of the next day. A family that does not know the Hebrew date can convert the civil date with our Jewish calendar or ask the burial society, which keeps records.

The day itself

Many visit the grave on the yahrzeit, give charity and sponsor a kiddush in the synagogue in memory of the deceased. A fast, where customary, is not held on Shabbat or Rosh Chodesh.