Conception Date Calculator — Estimate When You Conceived

Enter your due date or LMP to estimate the conception date and conception window.

Conception Date Calculator

About This Conception Date Calculator

This Conception Date Calculator helps you estimate when fertilization likely occurred. If you know your due date, conception is typically about 266 days before delivery. If LMP is known, conception usually falls around LMP + (cycle_length - 14). Use this for planning, personal records, or when discussing timelines with your provider.

Baby Gender Prediction Timeline

Once you know your conception date, you might be curious about when you can find out your baby's gender. Here's a timeline of when different methods become available:

Early Methods

  • NIPT: From 9 weeks (99% accurate)
  • Nub Theory: 12-14 weeks via ultrasound (75% accurate)

Standard Methods

  • Ultrasound: 18-20 weeks (95-99% accurate)
  • Traditional Methods: Any time (for fun only)

For detailed information about gender prediction methods, including accuracy rates and how they work, visit Baby Gender Prediction Methods.

Related Tools

Ovulation Calculator

Calculate your most fertile days to increase chances of conception.
Due Date Calculator

Calculate your estimated due date based on your last menstrual period.
Pregnancy Week Calculator

Track your pregnancy progress week by week with important milestones.

Frequently Asked Questions

How precise is this estimation?

The conception date estimation is based on standard calculations and assumptions about regular menstrual cycles. It provides a good approximation but isn't exact. Sperm can survive up to 5 days, and ovulation can vary from the expected date, so the actual conception date might differ by a few days.

How long after conception can a pregnancy test detect pregnancy?

Most home pregnancy tests can detect pregnancy about 10-14 days after conception, which is typically around the time of a missed period. Some sensitive tests claim to work a few days before a missed period, but waiting until after a missed period generally provides more accurate results.

Can implantation make the date later?

Yes, conception refers to fertilization, but implantation (when the fertilized egg attaches to the uterine wall) occurs several days later, typically 6-12 days after conception. Pregnancy tests detect the hormone hCG produced after implantation, not at the moment of conception.

What if I used fertility treatment?

If you've undergone fertility treatments like IVF, the conception date might be more precisely known. In IVF, conception occurs when the embryo is fertilized in the lab, and the transfer date is documented. This calculator may not be accurate for assisted reproductive technology cases.

Why does conception date matter?

The conception date helps healthcare providers track fetal development, determine accurate gestational age, and plan appropriate prenatal care. It's also useful for personal records and understanding your pregnancy timeline.