Menstrual Cycle Length Calculator — Is My Cycle Normal?
Determine your cycle length and whether it falls within the healthy range.
Frequently Asked Questions — Menstrual Cycle Calculator
What is a normal menstrual cycle length?+
A normal cycle ranges from 21-38 days, with the average being 28-29 days. Cycles outside this range consistently (>3 cycles) may indicate hormonal imbalances. Brief variations of 1-4 days are completely normal and expected from month to month.
Does cycle length affect fertility?+
Yes. Short cycles (<24 days) often mean early ovulation, giving sperm less time to reach the egg. Long cycles (>35 days) may indicate delayed or absent ovulation (anovulation). Optimal fertility is associated with cycles of 26-32 days. PCOS is the most common cause of long, irregular cycles.
Can cycle length change as you age?+
Yes — cycle length naturally changes throughout life. Teens often have irregular 28-45 day cycles. Adult cycles stabilize to 25-32 days in the 20s-30s. Perimenopause (40s) brings increasing irregularity. Cycle length variability begins increasing around age 40 as FSH rises and follicle quality declines.