Fertility, Conception & Ovulation Calculator
Estimate your fertile window, ovulation date, best conception days, next period and pregnancy test timing.
Hit Calculate to see your cycle phase
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Irregular cycles, recent hormonal contraception, breastfeeding, illness and stress can shift ovulation timing.
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Test a different cycle or luteal length without changing your main result.
Calculate your baseline first
It estimates ovulation by subtracting the luteal phase from your average cycle length. The fertile window starts about five days before estimated ovulation and includes ovulation day plus the selected post-ovulation day.
Calendar estimates are less reliable with irregular cycles. Use several months of cycle data and consider LH tests, cervical mucus observations or clinician guidance for more precise timing.
A practical test date is around the expected period or about 14 days after estimated ovulation. Testing too early can produce false negatives.
Results are calendar-based estimates generated locally in your browser for informational purposes only. They are not medical advice, contraception guidance, fertility diagnosis or a substitute for care from a qualified clinician.