Period Calculator
Predict your next 3 periods, ovulation days and fertile windows from your last period date
Enter Your Cycle Details
Most cycles are 21–45 days (average 28).
Your Predictions
Predicted period 1
Fri, Oct 2, 2026
Fertile window
Sun, Sep 13, 2026 – Fri, Sep 18, 2026
Ovulation day
Fri, Sep 18, 2026
Predicted period 2
Fri, Oct 30, 2026
Fertile window
Sun, Oct 11, 2026 – Fri, Oct 16, 2026
Ovulation day
Fri, Oct 16, 2026
Predicted period 3
Fri, Nov 27, 2026
Fertile window
Sun, Nov 8, 2026 – Fri, Nov 13, 2026
Ovulation day
Fri, Nov 13, 2026
About this Tool
This period calculator estimates your next three period start dates from the first day of your last period and your average cycle length. It also flags each cycle's fertile window and likely ovulation day (about 14 days before the next period), which is useful for planning or cycle awareness.
Common Use Cases
Plan Ahead
See upcoming period dates for travel, events and everyday planning.
Cycle Awareness
Track fertile windows and ovulation when trying to conceive — or avoid pregnancy with backup methods.
Spot Irregularities
Compare predictions with actual dates to notice skipped or unusually short cycles.
Doctor Visits
Bring a record of recent cycles when discussing menstrual health with your provider.
Pro Tips
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Track 3+ Cycles
Averages from several months predict better than a single cycle — cycles naturally vary by a few days.
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Fertile Window Basics
The 6 days ending on ovulation day are the most fertile; sperm can survive up to 5 days.
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Not Medical Advice
Predictions are estimates, not a diagnosis or contraception. See a doctor for irregular, missed or painful periods.
FAQs
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