Day of the Year Calculator
Quickly determine a date’s position within the year. Perfect for Julian day lookups, goal tracking, or annual planning.
Tuesday, November 25, 2025
Day of year: 329 / 365
Days remaining: 36 (37 including today)
Percent of year complete: 90.14%
Quarter: Q4
Week of year: 47 (ISO Week 48, 2025)
How to Use This Calculator
Select a date
Pick any date in the calendar to instantly see its ordinal position within the year.
Check year progress
Use the percent complete to gauge how far through the year you are—helpful for goal tracking or quarterly reports.
Leverage calendar context
The calculator also shows quarter and ISO week number, making it easy to align with fiscal calendars or project schedules.
Formula
Day of Year = floor((Date − Jan 0) ÷ 86,400,000)
Days Remaining = Days in Year − Day of Year
Percent Complete = (Day of Year ÷ Days in Year) × 100
Example: 2025-11-09 → Day 313 of 365 • 85.75% of the year complete • 52 days remain.
Why Day-of-Year Matters
Many industries rely on ordinal dates—weather services, agriculture, finance, and aviation all prefer day-of-year because it avoids month/day ambiguity.
- Track annual goals by comparing the day-of-year across multiple years.
- Coordinate multi-country projects without worrying about MM/DD vs DD/MM confusion.
- Plan marketing campaigns based on quarter and week numbers.
- Align engineering releases with specific ISO weeks.
Frequently Asked Questions
Does it handle leap years?
Yes. The calculator automatically switches to 366-day years when appropriate.
What about ISO week vs regular week?
Both are displayed. ISO weeks start on Monday and may belong to the previous/next year, which is reflected in the label.
Can I export results?
Copy the summary values into documents or spreadsheets. Automation hooks can be added later if needed.
Is the percent complete exact?
It’s based on the proportion of days elapsed. For more precision (including partial days), convert the date difference to hours.