Ovulation Estimator

Estimate ovulation day and fertile window from your last period.

First day of last period:

Cycle length (days):

⚠️ This is a personal log only — not medical advice, not a diagnosis. See a healthcare professional for any concern.

How to use

Enter the first day of your last period and cycle length, then click Estimate. Everything runs in your browser.

How accurate is this?

It's calendar math (ovulation ≈ 14 days before next period). Real cycles vary.

Is this medical advice?

No — an estimate only. Talk to your doctor for family planning.

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