🛠️ Japanese Memorial Service Date 計算機

Jurisdiction: Japan. This tool computes the dates of the customary Japanese Buddhist memorial services (houji / nenki-hoyo) that families observe after a person's death. The choice of which anniversaries are observed, and the Japanese counting convention in which the n-th memorial falls in the (n-1)-th year after death, are a Japan-specific cultural and religious custom. It is not a general international tool.

Choose the era of the death date (CE/Western, Meiji, Taisho, Showa, Heisei or Reiwa), enter the year number in that era, then pick the month and day. Choose whether you want the exact death-anniversary date, or the default "nearest Sunday on or before the anniversary" so the gathering can be held on a weekend before the true anniversary (shotsuki-meinichi). Era input is meaningful only from 1873 onward, when Japan adopted the Gregorian calendar.

The day-count services count the day of death itself as day 1: the 49th-day service is the death date plus 48 days, and the 100th-day service is plus 99 days, with the calendar rolling over months and leap years. The year-anniversary services use the kaiki rule: the 3rd memorial is in year Y+2, the 7th in Y+6, the 13th in Y+12, and so on, because the death year counts as the first in the kaiki sequence. The 1st anniversary (isshuki) is the literal one-year mark, Y+1.

Death date Showa 50, June 15 = Gregorian 1975-06-15 (a Sunday). The 49th-day falls on 1975-08-02, the 100th-day on 1975-09-22, the 1st anniversary on 1976-06-15, the 3rd memorial on 1977-06-15, and the 50th memorial on 2024-06-15. In Sunday mode each of these steps back to the nearest preceding Sunday.