About this tool
This tool returns the moon phase and illumination percentage for any date — past, present, or future — and renders a visual monthly grid showing a clean SVG phase mark for every day of the chosen month. Use it to plan astrophotography, fishing trips, religious observances, or simply to satisfy curiosity about tonight\'s moon.
How the calculation works
The Islamic Hijri calendar begins every lunar month at the new moon, so the Hijri day number (1–30) is a direct proxy for the moon\'s age in days. The page converts the chosen Gregorian date to its Hijri date via the Aladhan calendar API, then derives:
- Phase name — by mapping the moon\'s age (0–29.53 days) to one of the 8 traditional phase buckets.
- Illumination percentage — using the standard formula (1 − cos(2π × age / 29.53)) / 2, which gives 0% at new moon and 100% at full moon.
- Waxing or waning — based on whether the Hijri day is before or after the 15th.
The 8 moon phases
New Moon (age 0) → Waxing Crescent → First Quarter (age 7) → Waxing Gibbous → Full Moon (age 14.77) → Waning Gibbous → Last Quarter (age 22) → Waning Crescent → back to New Moon. A complete cycle (a synodic month) takes 29.53 days.
Worked example
On 1 Ramadan 1447 AH (≈ 20 March 2026 in the Umm al-Qura calendar) the moon is exactly at the New Moon — 0% illumination. By the 14th of Ramadan it reaches Full Moon (100% illumination), and on the 27th — Laylat al-Qadr — it is a thin waning crescent in the pre-dawn sky.