About Weekstamp

A complete day label for a weekly system.

Weekstamp is one free browser-local converter between Gregorian calendar dates and ISO week dates. It helps make weekly labels inspectable by showing the week-year, week number, weekday and available Monday/Sunday endpoints beside the original calendar day.

One focused conversion

Use a full date such as 2021-01-01, or a full ISO week date such as 2020-W53-5. The result identifies the same civil day in both forms. When the ISO week-year differs from the calendar year, the page makes that difference visible instead of quietly borrowing the wrong year.

The model is proleptic Gregorian years 0001–9999 with Monday-first ISO weeks. It does not use a current device date, timezone, timestamp, holiday lookup or custom business calendar. An endpoint outside the supported year range remains unavailable; impossible input dates and invalid week numbers are rejected.

Inspectable method and checks

The method explains the first-Thursday rule, exact integer day arithmetic and strict accepted forms. Original worked examples cover preceding/following ISO years, week 53, century leap years and the upper supported range. This is not a universal parser for every possible ISO 8601 representation.

Free use and contact

No account or payment is required. Optional notes and JSON are generated locally. Publisher verification metadata and ads.txt are prepared, but this source release contains no active analytics, advertising or consent-platform loader. Account setup, review and actual ad serving are separate from metadata.

The owner uses an existing shared public forwarding alias across the free-tool collection: yardfill.helpful594@aleeas.com. It is not a new mailbox. Use the contact page for reproducible issues and privacy for local input and export behavior.