Pregnancy Conception Calculator

Calculate your conception date and track important pregnancy milestones including fertile window, ovulation, and implantation dates.

Calculate Conception

Estimated date of delivery

Enter your information using any calculation method, then click Calculate to see your conception date, fertile window, ovulation, implantation dates, and comprehensive pregnancy timeline.

Complete User Guide

What is Conception?

Conception occurs when a sperm fertilizes an egg, typically happening during ovulation. This is the moment when pregnancy begins. The fertilized egg then travels to the uterus and implants in the uterine lining, usually 6-12 days after conception.

Understanding your conception date helps you track your pregnancy timeline more accurately and provides insight into when important milestones occur.

Key Concepts

Conception Date

The date when the sperm fertilized the egg. This typically occurs during ovulation, approximately 14 days after the start of your last menstrual period (for a 28-day cycle).

Fertile Window

The 6-7 day period when conception is most likely. Includes 5 days before ovulation, the day of ovulation, and 1 day after. Sperm can survive up to 5 days in the female reproductive tract.

Ovulation

The release of a mature egg from the ovary. This is your most fertile day. The egg survives for 12-24 hours after release, so timing intercourse around ovulation is crucial for conception.

Implantation

When the fertilized egg attaches to the uterine lining. This typically occurs 6-12 days after conception. Implantation bleeding (light spotting) may occur but is not always present.

How to Use This Calculator

  1. Choose your calculation method: From Due Date, From Last Menstrual Period, or From Conception Date
  2. Enter the required date information based on your selected method
  3. If using LMP method, enter your average cycle length (default is 28 days)
  4. Click 'Calculate' to see your conception date and comprehensive timeline
  5. Review fertile window, ovulation date, implantation window, and pregnancy status
  6. Use the charts to visualize your pregnancy progress and timeline

Understanding Your Results

Conception Date

The estimated date when conception occurred. This is calculated based on your due date, LMP, or known conception date. Conception typically occurs during ovulation, approximately 14 days after the start of your last period.

Fertile Window

The 6-7 day period when conception was most likely. This includes 5 days before ovulation, the day of ovulation, and 1 day after. Having intercourse during this window maximizes chances of conception.

Implantation Window

The period when the fertilized egg typically implants in the uterine lining (6-12 days after conception). Some women may experience light spotting during this time, known as implantation bleeding.

Weeks Pregnant vs Weeks Since Conception

Pregnancy is counted from the first day of your last menstrual period (LMP), not from conception. This is why you're considered 2 weeks pregnant at conception. Weeks since conception is the actual time since fertilization occurred.

Pregnancy Timeline

  1. 1. Last Menstrual Period (LMP) - Day 1 of pregnancy
  2. 2. Fertile Window Begins - 5 days before ovulation
  3. 3. Ovulation - Release of mature egg (most fertile day)
  4. 4. Conception - Sperm fertilizes egg (typically on ovulation day)
  5. 5. Implantation - Fertilized egg attaches to uterus (6-12 days after conception)
  6. 6. Due Date - Approximately 266 days from conception or 280 days from LMP

Important Notes

  • Conception dates are estimates. The exact moment of conception cannot be determined with certainty, but it typically occurs during the fertile window, most likely on or near the day of ovulation.
  • Pregnancy is calculated from the first day of your last menstrual period (LMP), not from conception. This is why you're considered 2 weeks pregnant at conception.
  • Implantation bleeding is light spotting that may occur 6-12 days after conception. Not all women experience this, and it's different from menstrual bleeding.
  • This calculator is for informational purposes only and should not replace professional medical advice. Always consult with qualified healthcare providers (OB/GYN, midwife, or family doctor) for pregnancy care, concerns, or questions.

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