Week number calculator online

How it works

Find the week number for any date.

We normalize civil dates to avoid timezone and daylight-saving errors.

How the week number is determined

Weeks begin on Monday and follow the international weekly calendar. Around New Year, some dates can belong to the final week of the previous year or the first week of the next one.

The result shows the week number and its corresponding year without unnecessary technical wording.

Tips for a useful result

Check the displayed year for dates near the beginning of January.
Use the monthly calendar to see where the date appears.
Week numbers are useful for planning, production and work schedules.

Example

Enter the values and get an instant result.

Frequently asked questions

Is the result exact?

Day and date calculations are exact. Values shown as months, hours or minutes may be approximate where appropriate.

Which parts of the result are exact?

Dates and calendar-day totals are exact. Conversions to months, weeks, hours or minutes may be approximate when there is no single calendar conversion.

Are my dates sent to the server?

No. The calculation runs in your browser, and entered values are not included in server requests or analytics events.

Can my timezone change the result?

The tool uses civil dates without a time and normalizes them internally, avoiding one-day shifts caused by timezones or daylight-saving changes.

Does it work on phones and computers?

Yes. The interface is responsive and uses features supported by modern desktop and mobile browsers.