Period & Ovulation Calculator
Understanding your cycle helps you plan or avoid pregnancy naturally. Our calculator predicts your next period, ovulation day, and fertile window based on your cycle data.
What Is
A period and ovulation calculator tracks your menstrual cycle to predict future periods, ovulation dates, and fertile windows. It uses your cycle length and period start date to make predictions.
How to Use
- Enter the start date of your last period
- Enter your average cycle length (default 28 days)
- Enter your average period length (default 5 days)
- Click Calculate to see your predictions
- View your fertile window, ovulation day, and next period dates
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Frequently Asked Questions
When do I ovulate?
Ovulation typically occurs about 14 days before your next period. In a 28-day cycle, that's around day 14.
How long is the fertile window?
About 6 days: 5 days before ovulation plus the day of ovulation itself.
How accurate is this calculator?
It works best for regular cycles (28-30 days). Irregular cycles make predictions less reliable.
What affects cycle length?
Stress, illness, travel, weight changes, and hormonal conditions can all affect your cycle.
Can I use this to conceive?
Yes, tracking ovulation helps identify your most fertile days. But it's not a substitute for medical fertility advice.