Pink Mom MathCycle Length Analyzer
Enter your period start dates to get a cycle consistency score (0–100) and see a chart of your individual cycle lengths.
Add at least 3 period start dates to see your cycle analysis.
How the Cycle Length Analyzer Works
The analyzer computes the interval between each consecutive pair of period start dates, then calculates the mean and population standard deviation of those intervals.
Consistency Score Formula
Score = max(0, round(100 – SD × 12)). This means every 1-day increase in cycle variability (SD) reduces the score by about 12 points. A score above 90 indicates very reliable cycle timing; below 50 suggests significant irregularity.
What the Bar Chart Shows
Each bar represents one cycle interval (the gap between two consecutive period start dates). Bars within one standard deviation of the mean appear in blue; outlier cycles appear in orange. The mean is shown as a reference.
Frequently Asked Questions
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Related Guides
PCOS and Fertility: What to Know About Irregular Cycles
How PCOS affects ovulation, cycle length, and conception. Learn strategies for tracking irregular cycles and when to seek fertility support for PCOS.
What Your Cycle Length Tells You About Your Health
A guide to interpreting your menstrual cycle length — what is normal, what signals irregularity, and how cycle patterns reflect hormonal and overall health.
Period Irregularity: When to See a Doctor
Know the difference between normal cycle variation and irregular periods that warrant medical attention. Covers missed periods, spotting, very short or long cycles, and red flags.
This calculator provides estimates for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health or your baby's health.
Cycle analysis provides statistical patterns from your entered data. Irregularities may warrant evaluation by a healthcare provider.