Guides & articles
Clear, practical guides on week numbers, the ISO 8601 standard, pregnancy weeks and the calendar tools we build.
11 articles · Page 1 of 2
World Cup 2026 calendar with all 104 games, flags, dates and kickoff times. Download the full schedule as an .ics and a…
Week Number API: a free REST endpoint that returns the ISO 8601 week number for any date. No key, CORS enabled, with JS…
What quarter is it? Right now it's Q2 2026, running April 1 to June 30. See exact Q1, Q2, Q3 and Q4 dates for 2026, plu…
Zero Waste Week 2026 runs Monday September 7 to Sunday September 13, the first full week of the month (ISO week 37). He…
Work weeks in a year come to about 52, or 261 weekdays in 2026. See working day totals for the US, UK, Canada and Austr…
Calculate the week number in Excel, Google Sheets, and Python with ISOWEEKNUM, WEEKNUM, and isocalendar(). Copy-paste f…
Week numbers 2026 in one place: the full ISO 8601 calendar of all 53 weeks, with exact Monday-to-Sunday dates for every…
US vs ISO week numbers, compared: ISO weeks start Monday with a first-Thursday rule; US weeks start Sunday and put Janu…
The third trimester starts at week 28 of pregnancy and runs to week 40 or birth. Get the full trimester-by-week breakdo…