Weeks Left to Live Tools Calendar What week is it?

About FailFlow Tools

FailFlow Tools is a set of small, fast calculators for the questions people ask about time every day: how long until a holiday, what date it will be in two weeks, which week of the year it is, how much of the year is left.

Written and maintained by the FailFlow Tools team · Page last reviewed October 4, 2026

How the numbers are calculated

  • Days are calendar days from today to the date — the start day is not counted, the end day is.
  • Weeks are whole 7-day blocks plus leftover days; months are whole calendar months counted from today's date.
  • Weekends count each Saturday once; business days count Monday to Friday and do not subtract public holidays.
  • Week numbers follow ISO 8601 (Monday start; week 1 contains the first Thursday).
  • Today is calculated for US Eastern time on our server, then re-checked in your browser against your own date.

Sources

  • US federal holidays: the rules in federal law (5 U.S.C. 6103), including the weekend "observed" shifts.
  • Jewish holidays (Rosh Hashanah, Yom Kippur, Passover, Hanukkah): the fixed Hebrew calendar; dates are the evening the holiday begins, checked against Hebcal.
  • Islamic holidays (Ramadan, Eid al-Fitr, Eid al-Adha): the commonly published observance dates, compared with the Umm al-Qura calendar via AlAdhan. These can move by a day depending on moon sighting.
  • Chinese New Year and Diwali: computed from astronomical new moons (Jean Meeus, Astronomical Algorithms) with each tradition's time zone and rules.
  • Easter: the Gregorian computus. Moon phases: Meeus' algorithm, accurate to a couple of minutes.
  • Week numbers: ISO 8601. Time zones: the IANA time-zone database, including daylight-saving changes.
  • Life expectancy: the US Social Security Administration Period Life Table, plus the peer-reviewed studies cited on each factor.

How we keep the numbers right

  • Every page is recalculated after midnight US Eastern time, and your browser re-checks the result against your own local date.
  • Every week the upcoming Jewish and Islamic holiday dates are compared with Hebcal and the Umm al-Qura calendar; differences are corrected automatically.
  • An automated check crawls every page of the site daily — broken links, wrong dates, redirects and errors are caught before readers see them.

Contact

Spotted a wrong date or want a new tool? Email failflow.com@gmail.com.