Conception Date Calculator
Estimate your likely conception window from a due date, or forward from your last period.
About this calculator
This calculator estimates a conception window — not a single exact day, since conception typically occurs within a few days around ovulation. From a due date, it works backward using the standard 280-day pregnancy length; from a last menstrual period, it assumes a typical 28-day cycle with ovulation around day 14. Actual cycle length and ovulation timing vary by person.
Frequently asked questions
- Why is this a window instead of one exact date?
- Conception can only happen within a few days around ovulation, and sperm can survive in the body for several days beforehand — so a ±3 day window is a more realistic estimate than pretending to know an exact day.
- Does this account for irregular cycles?
- No — it assumes a standard 28-day cycle with ovulation on day 14. If your cycle is significantly longer or shorter, your actual conception window will shift accordingly.
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🔒 All calculations run entirely in your browser — nothing you enter is ever sent anywhere. These are estimates based on standard averages, not medical advice — consult your healthcare provider for guidance specific to you.