Due Date Calculator – Estimate Your Pregnancy Due Date
Our due date calculator helps you estimate when your baby will arrive based on your last menstrual period, conception date, or IVF transfer date. Simply enter the relevant date and our tool will calculate your estimated due date, current week of pregnancy, trimester, and days remaining. Knowing your due date helps you plan prenatal care, prepare for birth, and track key pregnancy milestones.
Select how you want to calculate your due date.
Enter your last menstrual period start date, conception date, or IVF transfer date.
Only used with the LMP method. Default is 28 days.
Select embryo age at transfer. Only used with the IVF method.
Your results will appear here
How to Use This Calculator
1. Select your calculation method: Last Menstrual Period (LMP), Conception Date, or IVF Transfer Date. 2. Enter the corresponding date in the date field using the YYYY-MM-DD format. 3. If using the LMP method, adjust the average cycle length if yours differs from the standard 28 days. 4. If using the IVF method, choose whether your embryo was a Day 3 or Day 5 transfer. 5. Click Calculate to instantly see your estimated due date, conception date, current week of pregnancy, trimester, and the number of days remaining until your due date.
How Is a Due Date Calculated?
A typical pregnancy lasts approximately 40 weeks (280 days) from the first day of the last menstrual period (LMP). This standard is based on Naegele's Rule, the most widely used method for estimating a due date.
Naegele's Rule
Naegele's Rule adds 280 days (40 weeks) to the first day of the LMP. If your cycle is longer or shorter than 28 days, the estimated due date is adjusted accordingly. The formula is:
- Due Date = LMP + 280 days
- Adjusted Due Date = LMP + 280 days ± (Cycle Length − 28) days
Calculating from Conception Date
If you know your conception date, the due date is calculated by adding 266 days (38 weeks) to that date. Ovulation and conception typically occur about 14 days after the start of the LMP in a 28-day cycle.
IVF Transfer Date Method
For IVF pregnancies, the due date is calculated based on the embryo's age at transfer. For a Day 5 blastocyst transfer, 261 days are added to the transfer date. For a Day 3 cleavage transfer, 263 days are added. This accounts for the embryo's development before transfer.
Understanding Trimesters
Pregnancy is divided into three trimesters:
- 1st Trimester: Weeks 1–12. Major organ formation occurs. Morning sickness is common.
- 2nd Trimester: Weeks 13–26. The baby grows rapidly and movements become noticeable.
- 3rd Trimester: Weeks 27–40. The baby gains weight and prepares for birth.
Important Notes
Only about 5% of babies are born on their exact due date. A birth is considered full-term anywhere between 39 and 40 weeks, and early term from 37 to 38 weeks. Always consult your healthcare provider for a confirmed due date, especially following an ultrasound measurement.