Current week number

The week we are in right now, worked out from today’s date on your device — no server, no stale answer.

The current week number, under ISO 8601, is the number of the Monday-to-Sunday week containing today. Week 1 of an ISO year is the week with the year’s first Thursday, so the count is anchored to Thursdays, not to January 1 itself. That is also why the first days of January sometimes still belong to the old year’s week 52 or 53, and the last days of December can already be week 1 of the next year.

How this page stays current

Nothing here is fetched from a server. The page reads the date from your own device and runs the ISO Thursday rule on it, so the answer is correct whenever you open it — including the moment the week rolls over at midnight between Sunday and Monday. If your device clock is wrong, the week number will faithfully match that wrong date; the same calculation for any date you choose is on the week number calculator.

Common questions

When does the week number change?

At the start of Monday. All seven days from Monday to Sunday share one ISO week number; the count steps up as Monday begins. In US Sunday-start counting, the step happens a day earlier, at the start of Sunday.

Is the current week number the same everywhere?

The ISO number is the same for everyone on the same civil date — but two places can be on different civil dates at the same moment because of time zones, so for a few hours each day the “current” week can differ across the dateline. This page uses your device’s local date.

How many weeks are left this year?

Take the year’s total — 52 or 53 ISO weeks — and subtract the current week number. The year calendars list every week’s dates so you can see the rest of the year at a glance.