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Day of Year Converter

Convert dates to year-and-ordinal-day notation or restore dates from ordinal days.

Mode

Input

Result

Type or paste on the left — the result updates as you type.

Uses YYYY-DDD with 001-based days and Gregorian leap-year rules. Invalid day 366 values are rejected.

Up to 100,000 UTF-16 units per input and 1,000,000 per result. See the supported formats and examples below.

Format references

Tool page updated: