# Born January 1, 1990 — Hijri & All Calendars — Hijri Age Calculator

> 1 Jan 1990 in Hijri is 3 Jumada II 1410 AH. Full conversion in all 8 calendars: Hijri, Hebrew, Persian, Julian, Saka, Ethiopian, and Chinese.

- **Answer:** 1 Jan 1990 = 3 Jumada II 1410 AH
- **Category:** Date & Time
- **Interactive calculator:** https://youcalc.com/en/date-time/multi-calendar-age/born-in-1990-hijri-date/
- **Price:** Free, no sign-up required
- **Full calculator:** [Hijri Age Calculator](https://youcalc.com/en/date-time/multi-calendar-age/)
- **Pre-filled inputs:** `md=convert&sc=gregorian&by=1990&bm=1&bd=1`

| Metric | Value |
| --- | --- |
| Gregorian | 1990-01-01 |
| Hijri (Islamic) | 1410-06-03 |
| Persian (Solar Hijri) | 1368-10-11 |
| Julian | 1989-12-19 |
| Hebrew | 5750 Tevet 4 |


## Overview

January 1, 1990 falls on the 3rd of Jumada al-Akhira (Jumada II), 1410 in the Islamic Hijri calendar. The Hijri year is a lunar calendar about 11 days shorter than the Gregorian solar year, which is why a 1990 Gregorian date corresponds to an 1410 Hijri date rather than 1990. In the Persian Solar Hijri calendar the same date is 11 Dey 1368. Use the calculator below to convert any birth date — or any date — across all 8 calendar systems.

## Method

Every date is reduced to a Julian Day Number (JDN), a continuous integer count of days since a fixed epoch, and every output is derived from that single pivot. The Gregorian, Julian and tabular Islamic conversions are hand-rolled from the standard algorithms (Fourmilab / US Naval Observatory): the Gregorian and Julian use the classic civil-date formulas, and the tabular Hijri uses the 30-year cycle with 11 leap years and the leap rule ((year × 11) + 14) mod 30 < 11, anchored to the epoch JDN 1948439.5 (1 Muharram AH 1 = Friday 16 July 622 CE in the Julian calendar). The Hebrew, Persian, Indian (Saka), Ethiopian and Chinese calendars are read through Intl.DateTimeFormat's ICU calendars at the civil noon of each JDN, which yields an exact year and day; the total days lived is simply the difference of the two JDNs, so it is identical across calendars. Age in years is computed by counting completed calendar-year anniversaries up to the as-of date, clamping to the last valid day when a birthday lands on a date that does not exist that year (such as 29 February). The Hijri-drift figure compares the mean tabular Hijri year (10631 ÷ 30 ≈ 354.367 days) with the mean Gregorian year (365.2425 days), a deficit of about 10.876 days per year, and reports the approximate extra Hijri years your age accumulates. "Today" is computed at local civil midnight in your time zone, after the page mounts, so the default as-of date is correct wherever you are without baking a build-time date into the page.

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## Sources

- https://aa.usno.navy.mil/faq/islamic
- https://www.fourmilab.ch/documents/calendar/
- https://en.wikipedia.org/wiki/Tabular_Islamic_calendar

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