# Day of Year Converter

Convert any date to its day-of-year number (1-366) and back, with ISO week number, leap-year check, and days remaining in the year.

> Canonical page: https://elysiatools.com/en/tools/day-of-year-converter

- **Category:** Utilities

- **Keywords:** day of year, ordinal date, julian day, iso week, leap year, date converter, days remaining

## Overview

A bidirectional date ↔ ordinal converter. Enter a date to get its day-of-year number (e.g. Feb 1 = day 32), or enter a day number + year to get the calendar date. Each result also shows the ISO 8601 week number, whether the year is a leap year, how many days remain until year-end, and the day of the week. Useful for project tracking ("day 184 of 2026"), habit streaks, and log-file naming.

## Inputs

- **Conversion Mode** (select)
- **Date** (date): 2026-02-01
- **Year** (number)
- **Day Number (1-366)** (number): 32

## When to use

- Track schedules, milestones, or logs by ordinal day, such as day 184 of a year.
- Find the calendar date represented by a year and day number.
- Check ISO week numbers, leap-year status, and remaining days for a specific date.

## How it works

- Choose Date → Day of Year or Day of Year → Date.
- For date conversion, enter a calendar date such as 2026-02-01.
- For reverse conversion, enter a year and a day number from 1 to 366.
- Review the day-of-year result or calendar date along with ISO week, leap-year status, days remaining, and weekday.

## Use cases

- Project tracking that records milestones by ordinal day.
- Habit streaks and annual activity logs organized by day number.
- Log-file naming and date checks that require ISO week or year-end information.

## Frequently asked questions

### What is a day-of-year number?

It is the sequential position of a date within its year, from 1 to 365 or 366.

### Can I convert a day number back into a date?

Yes. Select Day of Year → Date and enter the year and day number.

### Does the converter support leap years?

Yes. It identifies leap years and supports day 366 in a leap year.

### What additional information does the result show?

The result shows the ISO 8601 week number, leap-year status, days remaining in the year, and weekday.

### What is day 60 in 2024?

Day 60 of leap year 2024 is February 29.

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