Advanced date and time calculationsElapsed time with zones, clock differences, averages, sorting and interval splitting.
Details of the first result
Dates & time
How it works
The Gregorian calendar uses leap years to align dates with the solar year. Years divisible by 4 are leap years, except centuries not divisible by 400: 2000 was leap, 1900 was not.
What you can do
Create a month or year calendar, choose the week start, and save an accessible printable calendar.
How to use it
- Enter a year from 1 to 9999. Select month or year view, choose a month if needed, and choose Monday or Sunday start. Calculate, then print or download SVG. The TXT version contains tab-separated calendar rows.
- Check the result and its notes. Copy or download only after calculating; any edit clears the old result.
Errors and limits
No public holidays, lunar dates or historical calendar switchovers are included. ISO week numbers appear for Monday start and use their own week year. Printing uses the browser’s print or Save as PDF dialog. SVG is a static image, not a subscription calendar.
All input stays in this tab. TXT files must be UTF-8; bulk input is limited to 200,000 characters and 10,000 lines.
Extensions: year searches ≤500years; date patterns ≤200,000days; clock patterns ≤24hours; result ≤10,000rows. Magic digits mean all equal or ascending with9→0 wrap. Choose the digit representation explicitly. Rounding ties choose the later boundary; ISO weeks start Monday. Date templates: [YYYY] [MM] [DD] [DDD] [W] [E]; clocks: [HH] [hh] [mm] [ss] [A]. Natural-language output uses your interface language. Gregorian Easter:1583–4099. Interval input: start / end.
Frequently asked questions
Why can early January belong to the previous ISO week year?
An ISO week starts Monday; week 1 contains the year’s first Thursday. Jan1 2021 is in ISO week 2020-W53. The Monday calendar includes the ISO week year so the boundary stays clear.
Are my dates uploaded or saved?
No. These calculations run in your browser. Inputs are not added to the address, stored between visits or sent to a server. Copy and download save only when you ask.