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Free period and cycle calculators

Quick answers to the cycle questions people search for most. Every calculation runs in your browser — nothing is uploaded, and there is no sign-up wall. Share your result as a card if it's useful to someone else.

Period calculator

Your next three period dates, fertile window and today's cycle phase from one date.

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Ovulation calculator

Estimate your ovulation day and the six-day fertile window around it.

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Cycle length check

Average, shortest, longest and how much your cycles vary — the numbers clinicians ask for.

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Calculators guess. Emmenia learns.

A free account turns these one-off estimates into forecasts built from your own logged cycles — plus pain tracking and a daily relief plan.

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These tools give estimates for general wellness planning. They are not contraception, not a pregnancy test and not medical advice.