Cycle Tracking Planner
Log at least two recent period start dates to calculate your average cycle length and forecast the next period and fertile days.
How to Use This Calculator
Track your period start dates
Record at least two consecutive periods. More data yields a more reliable average cycle calculation.
Adjust cycle length if needed
If you know your typical cycle length, override the average to maintain consistency in predictions.
Use predictions for planning
Utilize fertile window estimates for pregnancy planning or contraception awareness, and anticipate menstrual hygiene needs.
Formula
Cycle lengths = Difference in days between consecutive period start dates
Average cycle length = Mean of recorded cycle lengths
Next period = Most recent period start + Predicted cycle length
Fertile window approx Next period - cycle length + days 10 to 16
Full Description
Menstrual cycle tracking helps anticipate periods, evaluate cycle regularity, and plan conception. Average cycle length is calculated from the interval between consecutive period starts. Fertile windows generally occur 4 to 6 days before ovulation, which itself occurs about 12 to 16 days before the next period. Cycle irregularity can signal hormonal imbalances, stress, thyroid issues, or polycystic ovary syndrome - discuss persistent irregular cycles with a clinician.
Frequently Asked Questions
What if my cycles vary widely?
Significant variation may reduce prediction accuracy. Track additional cycles and consult a clinician if irregularity persists.
Can I use this for birth control?
Calendar tracking alone is less reliable than barrier or hormonal methods. Combine with ovulation signs if using fertility awareness.
How many cycles should I log?
Three to six cycles provide a solid baseline. Continue logging to monitor changes and patterns over time.
Should I track symptoms too?
Yes. Documenting cramps, flow, mood, or migraines helps correlate symptoms with cycle phases and informs discussions with healthcare providers.