Quick Tools
Ovulation Calculator
A calendar-based ovulation estimator. It uses last menstrual period and average cycle length to project ovulation (typically cycle length minus 14 days) and a six-day fertile window. Results are estimates for people with regular cycles, not medical advice or contraception.
Frequently asked questions
How is ovulation estimated?
For a regular cycle, ovulation is often estimated as 14 days before the next period. A 28-day cycle ovulates around day 14.
What is the fertile window?
Sperm can live several days. The fertile window is usually the five days before ovulation plus ovulation day.
Does this work with irregular cycles?
Estimates are less reliable if cycle length varies a lot. Tracking LH or basal temperature is more precise.
Is this birth control?
No. It is an estimate only and is not a method of contraception.
Is my data uploaded?
No. Dates stay in your browser.
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