Free Day of Year Calculator
Day 279 of 365 - but which date is that, and how many days are left in the year? Enter any date to get its ordinal day-of-year number, the days remaining in the year, its ISO week number and quarter. A small tool that answers surprisingly common planning questions in a single click.
How to Use the Day of Year Calculator
- Pick a date (or leave it as today).
- Click Calculate to see its day-of-year number.
- Also see days remaining in the year, ISO week and quarter.
Features
The headline number is the ordinal day of the year (1 to 365, or 366 in leap years), computed with leap-day awareness so dates after February 29 shift correctly. The result also shows how many days remain in the year, the ISO 8601 week number and the calendar quarter - four answers from one input.
Benefits & Use Cases
Manufacturing and food packaging use day-of-year codes for batch dating, fitness challengers track "day X of 365" goals, and finance teams confirm quarter boundaries. Teachers counting down school days and anyone running a year-long streak will find the remaining-days figure especially useful.
Tips
Remember that leap years shift every day number after February 29 by one, so always check the actual year rather than reusing last year’s numbers. Pair it with the Week Number Calculator for deeper ISO week detail, or Days in Month to see the full monthly context.
Frequently Asked Questions
What is the day of the year?
The ordinal number of a date within its year, from 1 (January 1) to 365 - or 366 in a leap year. October 6, 2026, for example, is day 279.
How do leap years affect the day number?
In a leap year, February has 29 days, so every date from March 1 onward is numbered one higher than in a common year.
What is day 100 of 2026?
April 10. Day 90 is March 31, so day 100 lands ten days into April.
How many days are left in the year?
The result shows the exact count of remaining days, which is handy for year-end planning and goal tracking.
Which quarter does a date fall in?
Q1 covers January to March, Q2 April to June, Q3 July to September and Q4 October to December. The tool labels it automatically.
Is this calculator free?
Yes - free, private and no sign-up, like every tool on NToolHub.
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