Day-Number.com is a free web-based calendar utility that instantly provides the current day number, ISO week number, and precise date information for any timezone worldwide.
What is Day-Number.com?
Day-Number.com is a free online tool that shows you today's day number (the sequential day of the year), ISO 8601 week number, and full date details based on your selected timezone or automatically detected location. Input any date or rely on real-time detection, and it outputs numeric day counts, week numbers, multi-format timestamps, and downloadable calendar graphics. The site is maintained by day-number.com and requires no account or installation.
Key Features
- Real-time timezone detection — Automatically detects your timezone via browser and adjusts day number, week number, and date displays instantly, supporting over 15 global timezones including EST, PST, GMT, CET, IST, JST, and more.
- ISO 8601 week number — Computes ISO 8601 week numbers (Monday start, Week 1 containing January 4) for any year, with accurate handling of 53-week years and year-boundary weeks.
- Day number for any year — Display the day number for today or any date from 1926 to 2125, including leap years (February 29 automatically counted as day 60).
- Multiple date calculators — Includes four interactive tools: Day Number Calculator (date ↔ day number), Week Number Calculator (date ↔ week number), Days Between Dates (exact day count between two dates), and Days From Today (future or past date from a number of days).
- Downloadable calendar images — High-resolution calendar graphics for 2026 showing day numbers or week numbers, available in fullscreen view and image download.
- Holiday data — Displays upcoming public holidays for the next 3 months for countries including the US, UK, Canada, Australia, and others.
- Multiple time and date formats — Shows timestamps in ISO 8601, RFC 2822, and Unix epoch (live updating), plus date in YYYY-MM-DD, YYYY-DD-MM, DD-MM-YYYY, and MM-DD-YYYY formats.
- Free embeddable widgets — HTML widgets to add day number, week number, and countdown timers to any website, with no coding required.
Who is it for?
- Project managers — Track sprint milestones across international teams using consistent day numbers and ISO week numbers.
- Finance and operations teams — Use week numbers for payroll cycles, fiscal deadlines, and compliance filings.
- Event planners — Count forward from today to lock venue holds, invitation sends, and reminder sequences using the Days From Today calculator.
- Legal and policy teams — Calculate statutory response periods or contract windows with the Days Between Dates calculator and export the record.
What can you do with Day-Number.com?
- Project managers: Plan sprints using day numbers, coordinate across time zones, and share calendar exports with teams.
- Finance teams: Set payroll runs and compliance deadlines based on ISO week numbers, even in 53-week years.
- Event planners: Use the Days From Today calculator to determine future dates for event milestones.
- Legal teams: Measure exact day counts between dates for contract periods and generate audit-ready records.
Frequently Asked Questions
What is a day number?
A day number is the count of days since January 1 of the given year. For example, February 1 is day 32. Day-Number.com calculates this automatically, handling leap years and timezones.
Why use day numbers instead of dates?
Day numbers provide immediate progress context (e.g., day 200 means 55% of the year is done) and simplify cross-timezone coordination.
How often does the data update?
The page updates in real-time upon each visit. Once your browser detects your timezone, all displays adjust instantly.
Does the tool work in leap years?
Yes, leap years automatically get 366 days, and the day number for February 29 is correctly shown as day 60.
Can I share results with my team?
Yes. You can copy the URL, download calendar images, or export tables to CSV for use in Slack or documentation.
