Ovulation Calculator
Find your ovulation date, fertile window, and due date
This tool estimates when you're likely to ovulate and your fertile window, based on your last period and cycle length. It's a rough prediction for planning or reference — not a guarantee.
Estimated Ovulation
Nov 5, 2026
Fertile Window
Oct 31 – Nov 6
Next Period
Nov 19, 2026
Estimated Due Date
Jul 29, 2027
if conception occurs
How to Use This Calculator
- Enter the first day of your last period.
- Enter your average cycle length in days.
- Review the estimated ovulation date, fertile window, and due date if conception occurred.
Why Use This Calculator?
- Timing intercourse around your fertile window.
- Tracking cycles to spot patterns.
- Getting a rough due-date estimate if you conceive.
Real-World Examples
A 28-day cycle
In a typical 28-day cycle, ovulation is often estimated around day 14, with the fertile window in the several days leading up to it.
How it's estimated
Ovulation typically falls about 14 days before your next period. The calculator estimates your next period from your cycle length and counts backward. Cycles vary, so the date is approximate.
Frequently Asked Questions
How accurate is the ovulation date?
It's an estimate. Ovulation can shift cycle to cycle, and stress, illness, and other factors affect timing. Ovulation predictor kits track hormones more directly.
Can I use this to avoid pregnancy?
It's not reliable for contraception. Sperm survives several days and ovulation can vary, so calendar methods alone are not dependable for preventing pregnancy.
Does it work for irregular cycles?
Less well. The estimate assumes a steady cycle length, so irregular cycles make the predicted date less dependable.
Important Disclaimer
Ovulation and fertile-window dates are estimates based on assumptions and are not medical advice or a reliable method of contraception. For fertility, cycle, or contraceptive guidance, consult a healthcare professional.
Privacy
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