Japanese Buddhist Memorial Service Calculator (Isshuki, Sankaiki, Nanakaiki)

Enter a date of death to instantly calculate the dates of Shonanoka, Shijukunichi, Isshuki, Sankaiki, Nanakaiki and other Japanese Buddhist memorial services, up to Sanjusankaiki. Also shows the nearest preceding Sunday for services that fall on a weekday.

Japanese Buddhist memorial services and their timing

Service	Typical timing	Overview
Shonanoka	7th day counting the day of death	Traditionally the day the deceased's spirit is said to reach the bank of the Sanzu River. Many families now fold it into the funeral day itself ("kuriage shonanoka").
Shijukunichi	49th day counting the day of death	Marks the end of the mourning period. Families commonly replace the temporary mortuary tablet with the permanent one and hold the burial of ashes around this date.
Isshuki	1 full year after death	The first anniversary of the death date, usually attended by a wider circle of relatives and friends and held on a relatively larger scale.
Sankaiki	2 full years after death	Because the year of death itself counts as the "1st" service, the 2-year mark is the "3rd" — hence "sankaiki". Still commonly held with a fair number of guests.
Nanakaiki	6 full years after death	From this point on, services are usually scaled down and gradually limited to immediate family.
Jusankaiki	12 full years after death	Often coincides with a generational handover of who organises the service, so it tends to be simplified further.
Jushichikaiki	16 full years after death	Some regions and sects skip this service and fold it into the next one instead.
Nijusankaiki	22 full years after death	Increasingly common to skip, but worth checking against your temple's specific customs.
Sanjusankaiki	32 full years after death	Often treated as the "toi-age", the final formal memorial service. Most families do not hold individual services beyond this point.

What is a Japanese memorial service schedule?

A Japanese Buddhist memorial service ("hoyo") is a ceremony held at fixed intervals after a death, both in the days right after (Shonanoka, Shijukunichi) and, over the following decades, on annual "kaiki" anniversaries such as Sankaiki and Nanakaiki. The counting convention is unusual: the year of death itself counts as the first service, so Isshuki alone means one full year later, while Sankaiki — despite the "san" (three) — falls only two full years after death. This makes the arithmetic easy to get wrong when planning by hand.

This tool takes a single date of death and calculates all nine services from Shonanoka through Sanjusankaiki at once. Where a service date falls on a weekday, it also shows the nearest preceding Sunday, reflecting the common practice of moving a memorial service earlier so relatives can attend more easily.

How to use this calculator

Enter the date of death Pick the date from the calendar.
Review the full schedule All nine memorial dates, from Shonanoka to Sanjusankaiki, appear automatically.
Check the earlier alternative For any date that falls on a weekday, the nearest preceding Sunday is shown as a common alternative — confirm the actual date with your temple and family.

Tips for getting more out of it

It's customary to hold the service on the Sunday before the exact date rather than after it, even if the date itself doesn't fall on a weekend. Some temples do offer a later weekend instead, so it's worth checking in advance.
From Sankaiki onward, the kaiki number is always "years since death, plus one" — Sankaiki is 2 years, Nanakaiki is 6 years. Keeping that in mind makes it easy to double-check any invitation you receive.
Shijukunichi is an important milestone that often coincides with the burial of ashes and replacing the temporary tablet, so it's worth starting to coordinate with your temple and relatives well in advance.
Some sects skip services after Nanakaiki, or treat Gojukkaiki (50 years) rather than Sanjusankaiki as the final service. Check your temple's specific sect and customs beforehand.

When this calculator helps

Booking a temple in advance

Knowing the candidate dates ahead of time makes it easier to secure a booking with the priest before weekend slots fill up.

Writing invitations to relatives

Get the exact date for an Isshuki or Sankaiki invitation calculated automatically from the date of death.

Coordinating Shijukunichi with the burial of ashes

Identify the Shijukunichi date early so you can plan the burial of ashes and the tablet replacement well ahead of time.

Memorial service terms explained

Shotsuki meinichi: The monthly date matching the day of death (same month and day). Annual memorial services are held on this date.
Kiake: The end of the mourning period, marked by Shijukunichi. Traditionally the point at which mourning clothing is set aside.
Toi-age: The final memorial service, after which individual services for the deceased are no longer held. Commonly Sanjusankaiki or Gojukkaiki.
Seshu: The person who organises and pays for a memorial service — typically the same person who served as chief mourner at the funeral.
Kuriage shonanoka: The custom of holding the Shonanoka service, normally due 7 days after death, on the day of the funeral itself.

Frequently asked questions

Japanese Buddhist "kaiki" counting treats the date of death itself as the first memorial day. The date one full year later is technically the "2nd", but that one gets the special name Isshuki. The date two full years later is the "3rd", which is why it's called Sankaiki. From Sankaiki onward, the rule "years since death, plus one" holds consistently.

No. It's common to hold it on the nearest weekend before the actual date so relatives can attend more easily. Moving it later, rather than earlier, is generally avoided, so when in doubt, choose the earlier weekend.

This varies by region, sect and family. Many families scale services down to immediate family only from Nanakaiki onward, and some skip Jushichikaiki or Nijusankaiki entirely, folding them into the next scheduled service. It's common to consult your temple on this.

Individual memorial services for that person are usually discontinued, and the deceased is instead remembered as part of a joint ancestral memorial, such as at the spring and autumn equinox or Obon. Many families also combine the individual mortuary tablet into a collective ancestral tablet at this point.

Side Note — where the "kaiki" counting comes from

The fact that Isshuki means "one full year" while Sankaiki means "two full years" trips up almost everyone the first time they receive a memorial service invitation. The idea traces back to a Buddhist convention of counting the day of death itself as the first memorial day. The year of death is the "1st", the date one full year later is the "2nd" — and that particular anniversary is given the special name Isshuki rather than "Nikaiki". The date two full years later becomes the "3rd", hence Sankaiki.

The gaps between later services — six years, six years, four years, six years, ten years — are not evenly spaced, and that's also deliberate. Services are traditionally assigned to years that are multiples of the Buddhist-favoured numbers three and seven: Sankaiki, Nanakaiki, Jusankaiki, Jushichikaiki, Nijusankaiki, Nijushichikaiki and Sanjusankaiki. The uneven intervals fall out of that numbering scheme rather than from any simple rule of "every so many years".

Treating Sanjusankaiki as the final service is often linked to the number thirty-three's association in Buddhist teaching with the mercy of Amida Buddha and the thirty-three manifestations of Kannon, the bodhisattva of compassion. By this point, the deceased is considered to have moved from being an individual spirit to joining the collective ranks of family ancestors — which is why many families shift from individual memorial services to a joint ancestral memorial afterward.

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