Ovulation Calculator

Understand your menstrual cycle with a calendar estimate of ovulation and fertile days.

ⓘ Cycle-date estimates do not confirm ovulation. Do not use this calculator to avoid pregnancy or identify “safe days”.

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Calculate your cycle

First day of your last period

Usual cycle length (days)

Period bleeding duration (days)

How regular are your cycles?

Why are you tracking?

Breastfeeding, recently postpartum or using hormonal contraception?

Age group (optional)

Months trying to conceive (optional)

Saved calculations

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When trying to conceive

Consider sex every 1–2 days during the estimated fertile window if comfortable; there is no need to time one exact day.
A positive urine LH surge test can indicate ovulation may occur over the following 1–2 days; clear, slippery cervical mucus may also indicate fertility. Neither guarantees ovulation.
Take 400 micrograms (mcg) folic acid daily before and during early pregnancy unless your clinician recommends a different dose. Review medicines, vaccines and health conditions before pregnancy.
Eat varied balanced meals, stay active as appropriate, and avoid smoking and alcohol when preparing for pregnancy.

Seek a fertility evaluation after 12 months of trying if under 35, or after 6 months if age 35 or older. Seek advice sooner with irregular or absent periods or known fertility concerns.

When calendar estimates may not be suitable

Irregular cycles, postpartum or breastfeeding changes, PCOS, perimenopause, recent hormonal contraception or missed periods can make predictions unreliable.

If there is concern about pregnancy, use an appropriately timed pregnancy test and speak with a clinician. This calculator does not confirm whether you are ovulating.

Sources and clinical limitations

ASRM — Optimizing Natural Fertility ACOG — Fertility Awareness NHS — Fertility and Cycle CDC — Folic Acid

Educational estimate only. Not a pregnancy test, diagnosis, fertility treatment plan, or birth control method. Protect access to personal menstrual records.

Ovulation Calculator

Calculate your cycle

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