Your estimated due date (EDD) can be calculated from your last menstrual period, conception date, or IVF transfer date. Only about 5% of babies are born on their exact due date — most arrive within 2 weeks before or after.
Calculate Your Due Date
How to Calculate Your Pregnancy Due Date
This pregnancy due date calculator supports three input methods: last menstrual period (LMP), conception date, and IVF transfer date. The most commonly used method is LMP, which is why your OB/GYN typically asks for this date at your first appointment.
LMP Method
Enter the first day of your last menstrual period. The calculator adds 280 days (40 weeks) and adjusts for your cycle length if different from 28 days. For a 28-day cycle, due date = LMP + 280 days.
Conception Date Method
If you know your ovulation or conception date (from ovulation tracking or timed intercourse), enter that date. The calculator adds 266 days (38 weeks) from conception to estimate the due date.
IVF Transfer Method
For IVF pregnancies, select either Day 3 or Day 5 transfer and enter the transfer date. Day 5 (blastocyst) transfers add 261 days; Day 3 transfers add 263 days. Your fertility clinic may provide a slightly different calculation based on embryo age at time of freeze.
FAQ
Is this pregnancy due date calculator free?
Yes, completely free with no signup required.
Is my data safe?
Yes, all calculations run in your browser. No data is sent to any server.
How is the due date calculated from LMP?
Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This is the standard clinical method used worldwide. The 280-day estimate accounts for the average 14 days from LMP to ovulation/conception.
How accurate is the due date calculation?
The EDD is an estimate. Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after the EDD. Ultrasound dating (especially in the first trimester) is the most accurate method and may revise the LMP-based estimate.
What is the difference between gestational age and fetal age?
Gestational age counts from the first day of the last menstrual period — the clinical standard. Fetal age counts from conception, which is typically 2 weeks less than gestational age. When doctors say '8 weeks pregnant,' they mean 8 weeks gestational age (about 6 weeks since conception).
What are the three trimesters of pregnancy?
The first trimester is weeks 1–12 (conception through 12 weeks). The second trimester is weeks 13–27 (when most women feel best and the baby becomes visibly active). The third trimester is weeks 28–40+ (rapid growth, preparation for birth). Labor before 37 weeks is considered preterm.