Moon and the menstrual cycle
18 October 2026 at 12:00 UTC: first quarter, 48.5% illuminated, 7.84 days since new Moon.
- Phase
- First Quarter
- Illumination
- 48.46%
- Lunar age
- 7.840 days
- Phase angle
- 88.08°
- Earth–Moon distance
- 403,106 km
- Brown lunation
- 1284
Recorded cycle starts
Entry date:2026-10-18 · UTC · 48.5% illuminated. Use the date controls above to select another entry date.
Two different cycles
A lunar phase cycle averages 29.53 days. Menstrual cycle length varies between people and from one cycle to another. In a 2021 study of 529 women aged 25–39, menstrual onset had no overall association with lunar phase.
Enter a recorded cycle-start date above to label it with its actual Moon phase. Tracking records a past event; a Moon phase does not determine ovulation, a fertile window or contraception timing.