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Kalkulator Daty Zapłodnienia

Reverse calculate the exact day you conceived, your 5-day intercourse window, and current gestational age based on clinical ultrasound or due date data.

Quick Clinical Summary

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Model Obliczeniowy Oparty na Dowodach Naukowych • Audyt: Październik 2026

Zweryfikowano przez: Zespół Badań Klinicznych i Metodologii Obliczeniowej Free Ovulation Tracker

Podstawa Literatury Źródłowej: Wilcox et al. (NEJM, 1995 & 1999) • Biuletyny Praktyki ACOG • Standardy Zdrowia Reprodukcyjnego WHO

Architektura Prywatności: 100% Wykonywanie w Przeglądarce po Stronie Klienta (Brak Zapisu na Serwerze)

Zobacz Naszą Metodologię Kliniczną i Źródła →

Conception Date & Intercourse Window Calculator

Reverse-calculate your exact conception day, intercourse window (5-day sperm survival), and current gestational progress.

Estimated Due Date (EDD)

Probable Ovulation & Conception Datepon., 24 sie 2026The exact 24-hour biological window when the mature oocyte was fertilized.

Likely Intercourse Windowśr. – pon.Accounts for up to 5 days of sperm survival in the fallopian tubes waiting for the egg.

Current Gestational Age & Due Date11w 3d • Due pon.First Trimester (Weeks 1–13)

Conception Date vs. Intercourse Date: The 5-Day Gap

A common clinical misconception is that conception must occur on the exact day of intercourse. In reality, human sperm can survive in fertile cervical mucus for up to 120 hours (5 full days). If sexual intercourse took place on Friday, fertilization may not have occurred until Wednesday afternoon when the follicle ruptured.

Planning Your Next Cycle or Predicting Future Ovulation?

For future cycle forecasting, fertile window alerts, and 6-cycle predictions, explore our primary Free Ovulation Tracker.

Free Ovulation Tracker

Frequently Asked Questions: Conception Timing

Clinical evidence on reverse-calculating conception from ultrasound scans and due dates.

How do you calculate conception date from due date?

Subtract 266 days (38 weeks of true fetal development) from your estimated due date (EDD).

Why is gestational age two weeks older than conception age?

Obstetricians count pregnancy starting from the first day of your last menstrual period (LMP), approximately 14 days before the egg was released and fertilized.

How accurate is an 8–12 week ultrasound scan?

First-trimester crown-rump length (CRL) sonography has a narrow biological variance of ±3 to 5 days, making it the most reliable clinical dating tool.

Could intercourse have occurred days before the conception date?

Yes. Sperm can survive up to 5 days in alkaline cervical crypts. Intercourse on O-5, O-4, O-3, O-2, or O-1 can fertilize an egg released days later.

Primary Fertility Hub