What it shows
| Item | Meaning |
|---|---|
| Day of the Gregorian year | Position counted from 1 January, e.g. “Day 266 of 365” |
| Left in the year | Days after this one until 31 December |
| ISO week | Week number and week-year under ISO 8601 |
| Quarter | Q1 (Jan–Mar) to Q4 (Oct–Dec) |
| Leap year | Whether the year has 29 February (366 days) |
| Day of the Hijri year | Position counted from 1 Muharram (Umm al-Qura) |
Examples
| Date | Day of year | ISO week |
|---|---|---|
| Wednesday 23 September 2026 | 266 of 365 | 39 of 2026 |
| Friday 1 January 2021 | 1 of 365 | 53 of 2020 |
| Tuesday 31 December 2024 | 366 of 366 | 1 of 2025 |
| Thursday 31 December 2026 | 365 of 365 | 53 of 2026 |
Days and weeks in a year
| Year | Days | In weeks | ISO weeks | Starts on |
|---|---|---|---|---|
| 2026 | 365 | 52 weeks 1 day | 53 | Thursday |
| 2027 | 365 | 52 weeks 1 day | 52 | Friday |
| 2028 (leap) | 366 | 52 weeks 2 days | 52 | Saturday |
The weekday a year starts on occurs 53 times in it; in a leap year the next weekday does too. A Hijri year is shorter: 354 or 355 days, or 50 weeks and 4 or 5 days.
Why week numbers differ between systems
Under ISO 8601 weeks start on Monday and week 1 contains the first Thursday, so a year has 52 or 53 weeks and early-January days can belong to the previous year. Many local calendars instead start weeks on Sunday and call the week of 1 January “week 1”. We use ISO because spreadsheets and business systems do.
For durations between dates use the Date Difference Calculator; for why some years have 366 days read Leap years and 29 February birthdays.
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