CYCLE REGULARITY

Menstrual Cycle Calculator

Enter consecutive period start dates to calculate your average cycle duration, day variance, and clinical regularity classification.

Cycle Parameters & Clinical Regularity FIGO Menstrual Criteria

Average Menstrual Cycle Length

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Regularity: —

Cycle Variance (Range)

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Difference between longest & shortest

Shortest / Longest Recorded

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Observed intervals

Clinical Interpretation

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Defining Clinical Cycle Regularity

The International Federation of Gynecology and Obstetrics (FIGO) Menstrual Disorders Committee defines normal menstrual cycle parameters in non-pregnant adult women aged 18 to 45:

Frequency (Length): 24 to 38 days (average 28 days).
Regularity (Variation): Variation of 7 to 9 days or less between the shortest and longest cycles across a 12-month period.
Duration: Normal bleeding lasting between 4.5 and 8 days.

When to Seek Clinical Evaluation

Consult a licensed gynecologist if your cycle lengths consistently fall below 21 days or exceed 35 days, if your periods stop for over 90 days (amenorrhea), or if bleeding lasts longer than 8 consecutive days.

References

Fraser IS, Critchley HO, Munro MG, Broder M. The FIGO recommendations on terminologies and definitions for normal and abnormal uterine bleeding. Int J Gynaecol Obstet 2011;113(1):3-7.