Calendar systems

Gregorian grid, second calendar underneath

In this release every calendar uses a Gregorian 2027 month grid. When you choose a second calendar, its date is printed under each Gregorian day. The months you select (for example February–April) are Gregorian months; a single Gregorian month can span two months — or even two years — of the second calendar, and the labels show that.

We do not yet offer calendars whose main grid follows another calendar's months. That is a separate product and will be labelled clearly if it is added.

How dates are calculated

Dates are computed by a stated method, never guessed by AI. The method in use is named on every preview under "Second-calendar method".

• Chinese lunar dates come from the Hong Kong Observatory's official 2027 Gregorian–lunar conversion table (HKO 2027 table, PDF). We use the table's month boundaries for every 2027 day, because a calculated (ICU) conversion disagrees with the official table on some 2027 dates. Unicode CLDR / ICU is used only for the wording: localized month and year names and numerals.
• All other second calendars are converted with the Unicode CLDR / ICU calendar definitions built into the runtime (Intl), anchored to the Gregorian civil date.

| Calendar | Notes | | --- | --- | | Chinese lunar | Hong Kong Observatory 2027 table (no leap month falls in 2027). Traditional festivals are not shown, and lunar dates are not public holidays. | | Japanese era | Era name and year (e.g. Reiwa 9 = 2027). | | Hijri (Umm al-Qura) | The Saudi Umm al-Qura tabulation. Actual dates in your country can differ by a day because of local moon sighting. | | Hijri (tabular) | An arithmetic calendar; it can differ from observed dates. | | Hebrew | Hebrew dates change at sunset; we show the date for the daytime of each Gregorian day. | | Persian (Solar Hijri) | The official calendar of Iran and Afghanistan. | | Thai Buddhist | Buddhist Era year (2027 = BE 2570). | | Minguo (ROC) | Year count used in Taiwan (2027 = Minguo 116). | | Indian national (Saka) | The Indian national civil calendar. |

Holidays

Calendar conversion, traditional festivals, public holidays and substitute workdays are different things. Our calendars show converted dates only: we do not infer or print festivals, public holidays or substitute workdays from a conversion, and nothing on a calendar is an official holiday schedule.

AI full images

When AI draws the whole calendar, it receives the same settings but may still draw wrong dates. Those images are always labelled "AI-drawn dates — not verified".