🧮 Calculators & Daily Life

Rokuyō Calendar

A monthly calendar of rokuyō — Japan's six-day cycle of lucky and unlucky days (Senshō, Tomobiki, Senbu, Butsumetsu, Taian, Shakkō). Check any date's rokuyō and its old-calendar date, and find upcoming Taian (best-luck) days. Everything runs in your browser.

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"M6" in a cell marks the first day of an old-calendar month (a new moon); ʼ marks a leap month.

Upcoming Taian days (popular for weddings & big purchases)

    How to use

    Move between months with the Prev / Next buttons — today is outlined. To look up a specific day, use "Check a specific date" and you'll get its rokuyō along with the corresponding date on Japan's old lunisolar calendar. Hunting for a good day for a wedding or a car delivery? The "Upcoming Taian days" list gives you the next best-luck dates at a glance.

    What is rokuyō?

    Rokuyō (六曜) is a six-day cycle of fortune labels that came to Japan from China and spread in the Edo period. Even today, many printed calendars in Japan show it, and it quietly influences real decisions: wedding halls are booked out on Taian days, funerals avoid Tomobiki ("pulling friends along"), and car dealers schedule deliveries around Butsumetsu. The cycle is not tied to the week — it follows the old lunisolar calendar, which is why it seems to "jump" mid-month whenever a new lunar month begins.

    RokuyōKanjiTraditional meaning
    Senshō先勝"First wins." Lucky in the morning, unlucky in the afternoon — good for urgent business.
    Tomobiki友引Lucky morning and evening, unlucky at noon. Funerals are avoided ("pulls friends along").
    Senbu先負"First loses." Unlucky morning, lucky afternoon — a day for keeping calm.
    Butsumetsu仏滅The unluckiest day of the cycle. Weddings tend to avoid it.
    Taian大安"Great peace." Lucky for everything — the most popular day for weddings and moves.
    Shakkō赤口Lucky only around noon. The "red" is associated with fire and blades — be careful.

    Examples

    • Old-calendar New Year's Day is always Senshō; the cycle then runs Tomobiki → Senbu → Butsumetsu → Taian → Shakkō.
    • February 17, 2026 is old-calendar January 1, so it is Senshō.
    • The sequence resets mid-month wherever a new moon starts a new old-calendar month.

    FAQ

    Is my data sent to a server?
    No. All rokuyō and old-calendar computations run in your browser; nothing is transmitted or stored externally.
    How is the rokuyō of a day determined?
    Mechanically, from Japan's old lunisolar calendar: add the old-calendar month and day, and the remainder when divided by 6 picks the rokuyō. New Year's Day on the old calendar is always Senshō, the cycle then advances one step per day, and it resets whenever an old-calendar month begins.
    Does this match printed Japanese calendars?
    The old calendar is computed astronomically from new moons and the sun's position, cross-checked against Japan's National Astronomical Observatory data to within about a minute. For the "2033 problem" (autumn 2033 to 2034), where the old calendar has no single official construction, this tool follows the resolution recommended by Japan's calendar industry — anchoring the month containing the winter solstice as month 11, which gives 2033 a leap 11th month — so calendars built on a different rule may disagree in that window.
    Which years are supported?
    Years 1900–2099. For dates far in the past or future, a day at a boundary could very rarely shift by one due to the nature of astronomical approximation.
    Is there any scientific basis to Taian and Butsumetsu?
    No. Rokuyō is a form of calendar divination with no scientific backing, but it remains a widely observed custom in Japan when choosing dates for weddings, car deliveries and moves.