Conception Calculator

Estimate your date of conception based on LMP or Due Date.

Select method and enter required date(s).

Conception typically occurs around ovulation, roughly 14 days before the next expected period. This calculator provides an estimate based on this average.

Estimating Your Conception Date

Pinpointing the exact date of conception can be difficult, as it depends on ovulation timing and sperm viability. However, you can estimate the likely conception date based on either the first day of your last menstrual period (LMP) or your estimated due date (EDD). This calculator provides estimates using these common starting points.

How to Use

  1. Select Method: Choose whether you want to calculate based on your Last Period or your Estimated Due Date.
  2. Enter Date(s):
    • If using LMP: Enter the first day of your last period and your average cycle length.
    • If using Due Date: Enter the estimated due date provided by your doctor or another calculator.
  3. Click Calculate: Press the button.

The calculator will display the estimated date of conception.

Calculation Methods

  • Based on LMP: Conception generally occurs around ovulation. Ovulation is estimated to be `Cycle Length - 14` days after the LMP. Therefore, the estimated conception date is roughly `LMP Date + (Cycle Length - 14) days`. For a standard 28-day cycle, this is `LMP Date + 14 days`.
  • Based on Due Date: A full-term pregnancy is considered 280 days (40 weeks) from the LMP, or 266 days (38 weeks) from conception. Therefore, the estimated conception date is roughly `Due Date - 266 days`.

Important Considerations

  • These are *estimates*. Actual ovulation and conception can vary.
  • Calculations based on LMP are less accurate with irregular cycles.
  • Due dates themselves are estimates, so calculating conception from an EDD adds another layer of estimation.
  • Early ultrasound measurements provide the most accurate dating of a pregnancy.

This tool offers a helpful estimate, particularly useful in early pregnancy or when planning based on cycle tracking.