Menstrual Cycle Calculator
NEWPredict your next period dates and ovulation window. Enter your last period date and cycle length to get your next 3 periods, fertile window, current cycle phase, and hormonal insights.
How to use
- 1Enter: last_period(YYYY-MM-DD),cycle_length — e.g. 2024-03-01,28
- 2Also accepts DD/MM/YYYY date format
- 3Optionally add period duration as 3rd param: 2024-03-01,28,5
Frequently Asked Questions — Menstrual Cycle Calculator
How do I calculate my menstrual cycle?+
Your menstrual cycle is counted from Day 1 of your period to Day 1 of your next period. The average cycle is 28 days, but normal ranges from 21-38 days. Track 3 cycles and average them for your personal cycle length.
When is a menstrual cycle irregular?+
Cycles shorter than 21 days or longer than 38 days, or varying by more than 7 days regularly, are considered irregular. Common causes include PCOS, thyroid disorders, stress, extreme exercise, and significant weight changes.
How accurate is a period calculator?+
Period calculators are most accurate for women with regular cycles. Stress, illness, significant weight change, and new exercise regimes can all shift your period by several days. Always track your actual cycle rather than relying only on predictions.