Period Calculator Online | Next Period & Ovulation Date

Period Calculator

Predict next period, ovulation, and fertile window based on your cycle.

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Enter your details

1st day of last period ℹ️

Use the first day of your most recent period.

Average cycle length ℹ️

Used to estimate next period and ovulation timing.

Period length ℹ️

Used to estimate the end date of your next period.

Tip: These are calendar estimates. Irregular cycles can reduce accuracy.

Results

Next period — start

Next period — end

Ovulation day (approx.)

Fertile window (approx.)

Educational use only — not medical advice. If your cycles are very irregular or you have concerns, consult a clinician.

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