Due Date Calculator
Calculate your estimated due date using your last menstrual period, conception date, or IVF transfer date — with current pregnancy week and progress tracking.
Calculate Your Due Date
💡 Baby This Week
Enter your dates to see your baby's development at this stage.
How It Works
This calculator estimates your due date the same way most healthcare providers do at your first prenatal visit. By default, it uses your Last Menstrual Period (LMP) and Naegele’s Rule: adding 280 days (40 weeks) to the first day of your last period, which assumes a standard 28-day cycle with ovulation around day 14.
If you know your conception date instead, the calculator adds 266 days (38 weeks) from that date, since conception typically happens about two weeks after LMP.
For IVF pregnancies, dating is based on the embryo transfer date rather than LMP, since the embryo’s exact age is already known: 261 days from a Day 5 (blastocyst) transfer, or 263 days from a Day 3 transfer.
None of these methods predict an exact birth date only about 5% of babies arrive on their estimated due date. What they give you is a starting point your doctor will refine using ultrasound measurements, especially if your cycle is irregular or conception timing is uncertain.
Frequently Asked Questions
How is my due date calculated?
The most common method uses your Last Menstrual Period (LMP): add 280 days (40 weeks) from the first day of your last period. If you know your conception date, add 266 days (38 weeks). For IVF, a Day 5 transfer adds 261 days; a Day 3 transfer adds 263 days from the transfer date.
How accurate is the due date?
Only about 5% of babies are born exactly on their due date. Most arrive within a window of 2 weeks before or after. The due date is an estimate your healthcare provider may adjust it based on early ultrasound measurements, especially if your cycle is irregular.
What if my cycle is not 28 days?
The LMP method assumes a 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, your actual due date may differ. For irregular cycles, using your conception date or early ultrasound dating provides a more accurate estimate.
Can I use this for IVF pregnancies?
Yes. Select the IVF Transfer tab and enter your embryo transfer date. For a Day 5 (blastocyst) transfer, we add 261 days. For a Day 3 transfer, we add 263 days. IVF due dates are generally very accurate since the exact transfer date is known.
What do the trimesters mean?
First trimester (weeks 1–13): Early development of organs, morning sickness, fatigue. Second trimester (weeks 14–27): Baby grows rapidly, movements felt, energy returns. Third trimester (weeks 28–40): Baby gains weight, prepares for birth, increased discomfort.
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⚠️ Medical Disclaimer: This calculator provides estimated due dates for informational purposes only. Every pregnancy is unique. Your healthcare provider will confirm your due date through clinical evaluation and ultrasound. This tool is not a substitute for professional medical advice.
