The Most Accurate Pregnancy Due Date Calculator - Natural or IVF

Find your due date based on your Last Menstrual Period (LMP), Conception Date, or IVF Transfer, and get ready to track every amazing week!

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  By: Tali Ditye, Ph.D., Co-founder

  Updated: October 23, 2025

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Pinpointing your due date is the first exciting step in your pregnancy journey. Our calculator provides a simple way to get a solid estimate and then maps out key developmental milestones for your baby and your body.

Use one of the calculation methods below and click Calculate Dates & Milestones to get started!

When you're done, check out our reviews of the best baby products of the year to find the perfect gear for your growing family!

Pregnancy Due Date Calculator with Milestones

Try the Calculator

Scroll up to use our comprehensive Due Date Calculator. You can input information based on your last menstrual period, conception date, or IVF/IUI transfer details to generate your Estimated Due Date (EDD). Once calculated, you'll see a complete timeline of your pregnancy, broken down by key developmental weeks.

Trying to get pregnant? Use our ovulation calculator tool to see your fertile window!

Methods for Due Date Prediction

Your healthcare provider will use one of the following methods to estimate your due date, depending on the information you have. Our calculator can use all of them to give you an accurate prediction:

1. Based on Last Menstrual Period (LMP): This is the most common method, also known as Naegele's Rule. It assumes a 28-day cycle and that ovulation occurred exactly 14 days after your period started. The calculation works by adding 280 days (40 weeks) to the first day of your last period. Example: 280 days after the start of your LMP.
2. Based on Conception Date: If you were tracking ovulation (or know the exact date of intercourse that led to pregnancy), this can be a very accurate method. Pregnancy is typically considered to be 38 weeks (266 days) from the date of conception. Example: 266 days after your conception date.
3. Based on IVF or Embryo Transfer: Assisted Reproductive Technology (ART) provides a very precise date for establishing your timeline.
   • Fresh Egg/IUI: For a fresh egg retrieval or Intrauterine Insemination (IUI), the due date is 266 days from the date of the procedure.
   • Day 3 Embryo Transfer (Cleavage Stage): Add 263 days to the date of the transfer.
   • Day 5 Embryo Transfer (Blastocyst): Add 261 days to the date of the transfer.
4. Using a Known Due Date: If your doctor has already given you an official due date, you can use that date to simply back-calculate your current week of pregnancy and see the detailed milestones timeline.

Key Pregnancy Milestones by Week

Once you calculate your EDD, the timeline will show you when to expect some of the most exciting moments and significant clinical benchmarks of your pregnancy (all dates are based on a 40-week timeline):

• Heartbeat may be detectable via ultrasound: Week 6
• First official prenatal appointment (usually): Week 10
• End of First Trimester (Increased Energy!): Week 13
• Quickening (First perceived movements): Week 18
• Halfway Point! (Anatomy Scan): Week 20
• Fetal viability benchmark (with intensive care): Week 24
• End of Second Trimester (The Golden Phase): Week 27
• Full Term Pregnancy begins: Week 37
• Estimated Due Date (EDD): Week 40
• Post-Term (Induction often considered): Week 42

What Does "Estimated Due Date" Mean?

It is important to remember that your Estimated Due Date (EDD) is just that, an estimate. Only about 5% of babies are actually born on their exact due date. The EDD is a guideline that helps your healthcare provider monitor your baby's growth and schedule important tests and appointments.

• The Range is Normal: A pregnancy is generally considered on track if the baby arrives anytime between Week 37 and Week 42.
• Early Scans are Best: The most accurate way to confirm or adjust your due date is through an early ultrasound (usually between 8 and 13 weeks), which measures the baby and provides the most reliable dating.

Full Term, Pre-Term, and Post-Term

Medical professionals use specific terms to categorize the timing of your baby's birth:

• Pre-Term: Before Week 37, often requiring specialized care.
• Early Term: Between Week 37, 0 days and Week 38, 6 days.
• Full Term: Between Week 39, 0 days and Week 40, 6 days. This is the optimal time for a baby to be born.
• Late Term: Between Week 41, 0 days and Week 41, 6 days.
• Post-Term: After Week 42, 0 days (or 14 days after the EDD), when induction is often discussed to reduce risks to the baby.

Disclaimer

Our Pregnancy Due Date and Milestone Calculator is for informational and entertainment purposes only. This tool provides an estimate based on common formulas; it is not a substitute for professional medical advice.

Always consult your healthcare provider to confirm your official Estimated Due Date and discuss all aspects of your pregnancy care.

References

American College of Obstetricians and Gynecologists (ACOG). (2021). Methods for Estimating the Due Date. acog.org.

National Institutes of Health (NIH). (2022). How Long is a Full-Term Pregnancy? nih.gov.

Society for Assisted Reproductive Technology (SART). (2020). Calculating Due Date After IVF. sart.org.