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Convert a birthday, a deadline, or today. Both dates identify the same day within the same year.
Your date is calculated in your browser. The converter does not send it to a calculation service. A shared link includes the date in its address.
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Both calendars begin the year together and have the same number of days. Conversion changes the month and day label, preserving the ordinal day (its position in the year).
Add the lengths of the completed months to the day of the month in the input calendar. January 1 is day 1.
Subtract complete months in the destination calendar until the remaining count fits inside a month.
The remainder is the day of that month. The year stays the same. For Metric dates, classify the day using the six-day pattern or extra-day rules.
Metric month lengths are 36, 37, 36, 37, 36, 37, 36, 37, 36, 37; the final value becomes 38 in a leap year. See the full month table and leap-year rule.
Worked examples
Gregorian day of year:31 + 28 + 31 + 30 + 31 + 30 + 1 = 182.
The first four metric months total 36 + 37 + 36 + 37 = 146 days. The remainder is 182 − 146 = 36.
g2026-07-01 = 2026-05-36
Radiate (month 05), metric week 6, Renew (Rest Day 2).
Load this example →Gregorian day of year:31 + 28 + 14 = 73.
Subtract the first metric month: 73 − 36 = 37. Day 37 of month 02 is outside the metric week.
g2026-03-14 = 2026-02-37
The first Bonus Rest Day of the year, in Awaken (month 02). It has no named metric weekday.
Load this example →| Gregorian | Metric | Why it matters |
|---|---|---|
| g2026-01-01 | 2026-01-01 | Shared start of year |
| g2026-02-05 | 2026-01-36 | Last day of metric month 01 |
| g2026-02-06 | 2026-02-01 | Next metric month begins |
| g2028-02-29 | 2028-02-24 | Gregorian leap day is a regular metric day |
| g2026-12-31 | 2026-10-37 | Common-year Bonus Rest Day / New Year’s Eve |
| g2028-12-30 | 2028-10-37 | Bonus Rest Day in a leap year |
| g2028-12-31 | 2028-10-38 | Leap Day / New Year’s Eve |
| g2100-12-31 | 2100-10-37 | 2100 is not a leap year |
Invalid examples: Metric 2026-01-37 (month 01 has only 36 days), 2026-10-38 (not a leap year), and Gregorian g2100-02-29 are rejected.
The converter uses Gregorian rules throughout years 1–9999, not historical local calendars. “Today” uses your device’s local date. For a recurring Gregorian birthday or holiday, convert each occurrence in its own year: after February, leap years can change the Metric month/day. Read the practical guidance.