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Date Inspector & ISO Week

Inspect a date’s weekday, ISO week number, quarter, day of year and leap-year status.

When to use this tool

How to use

  1. Select a date and review its calendar details.

Examples

Input: 2021-01-01
Result: Friday; common year; day 1; W53; Q1; 364 days left in the year. W53 belongs to ISO week-year 2020.
Input: 2024-12-30
Result: Monday; leap year; day 365; W1; Q4; 1 day left in the year. W1 belongs to ISO week-year 2025.
Input: 2024-02-29
Result: Thursday; leap year; day 60; W9; Q1; 306 days left in the year.

Before you start

Frequently asked questions

What should I check?

ISO weeks can differ from local or company week-number rules.

Why can January show W53 or December show W1?

ISO weeks start on Monday, and week 1 contains January 4. Around New Year, the ISO week-year can differ from the calendar year. This view displays only the W number, not a separate ISO week-year. Company week-number rules and fiscal quarters are not applied.

Do time zones or public holidays affect the result?

The selected date is calculated as a UTC calendar date for weekday and day counts. There is no time-of-day input or time-zone conversion here. It does not determine whether the date is a holiday, organizational closure or legal deadline.