Conception Calculator — Calculadora Online Grátis
Estimated conception date from due date or LMP with implantation window and pregnancy milestones
This calculator works both forward and backward: enter your last menstrual period to estimate when conception likely occurred, or enter your known due date to calculate backward to the probable conception date. It also shows the implantation window and key pregnancy milestones.
Frequently Asked Questions
Sobre Esta Calculadora
Conception occurs when a sperm cell fertilizes an egg, typically within 12–24 hours of ovulation. Because ovulation timing varies and sperm can survive in the reproductive tract for up to 5 days, the exact date of conception is rarely known with certainty — even with timed intercourse.
This calculator estimates conception based on the assumption that ovulation occurred on day 14 of a 28-day cycle. Women with longer or shorter cycles, or irregular ovulation, may have conceptions that fall several days before or after this estimate.
Healthcare providers typically confirm gestational age via ultrasound in the first trimester, which measures fetal crown-to-rump length to determine developmental stage more precisely than calendar methods. The LMP-derived due date and conception estimate are used as starting points until ultrasound data is available.
This calculator works both forward and backward: enter your last menstrual period to estimate when conception likely occurred, or enter your known due date to calculate backward to the probable conception date. It also shows the implantation window and key pregnancy milestones.
Exemplo Resolvido
Estimating conception date from a known due date of February 14, 2026
Entradas:
- Known due date: February 14, 2026
Passo a Passo:
- Due date − 280 days (Naegele's Rule in reverse) = LMP estimate
- February 14, 2026 − 280 days = May 10, 2025 (estimated LMP)
- Conception date = LMP + 14 days (average ovulation day)
- Estimated conception: May 24, 2025
- Implantation window: May 30 – June 5, 2025 (6–12 days post-conception)
- Earliest positive pregnancy test: approximately June 5–7, 2025