Menstrual Cycle Calculator
Menstrual Cycle Calculator pinpoints where you are in your cycle today — your cycle day, current phase and days to your next period — with a clear phase timeline.
Last updated: July 2026
A menstrual cycle calculator shows which day of your cycle you're on today, your current phase (menstrual, follicular, ovulation or luteal), and how many days until your next period.
How to use Menstrual Cycle Calculator
- Enter the first day of your last period.
- Set your average cycle length and period duration.
- See today's cycle day, phase and countdown to your next period.
Frequently asked questions
What are the cycle phases?
Menstrual (period), follicular (before ovulation), ovulation (around mid-cycle), and luteal (after ovulation until your next period).
How is my current phase found?
It counts the days since your last period started and maps that day onto the typical phases for your cycle length.
Is my data private?
Yes — all calculations run in your browser.
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