Ovulation Calculator
Estimate your ovulation day and fertile window from your cycle.
Estimate the likely ovulation day, fertile window and next period dates from the first day of your last period and your average cycle length.
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How to use Ovulation Calculator
- Enter your measurements.
- Select your activity level or goal.
- Review the estimate.
- Adjust over time based on real results.
Best for
- health workflows
- quick ovulation calculator tasks
- browser-based utility work
Tips for better results
- Estimates vary between individuals.
- This is not medical advice.
- Consult a professional for health conditions.
Frequently asked questions
How is ovulation estimated?
Ovulation is assumed about 14 days before the next period (the luteal phase, which you can adjust).
How long is the fertile window?
About six days: the five days before ovulation and the day of ovulation or after.
Is this accurate for irregular cycles?
No. It suits regular cycles only and is not contraception or medical advice.
Is my data sent to a server?
No. Everything is calculated in your browser, so what you enter stays on your device.
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