Pregnancy Due Date Calculator — Calculate EDD & Pregnancy Weeks | CalculHub
Pregnancy Due Date Calculator
Calculate your estimated due date (EDD), current week, and key pregnancy milestones.
Pregnancy Due Date Calculator — Calculate Your Estimated Delivery Date
A Pregnancy Due Date Calculator helps expectant mothers calculate their Estimated Due Date (EDD) based on the first day of their Last Menstrual Period (LMP). The due date is calculated by adding 280 days (40 weeks) to the LMP date — a method known as Naegele's Rule, which is the standard used by OBGYNs and midwives worldwide.
This calculator also shows your current pregnancy week, trimester, days remaining, and key milestone dates so you can plan doctor visits, scans, and baby preparation.
⚕️ Medical Disclaimer: This calculator provides estimates for informational purposes only. Always confirm your due date and pregnancy details with a qualified healthcare provider.
How is Due Date Calculated? (Naegele's Rule)
Naegele's Rule: Add 7 days to the first day of LMP, then add 9 months (or subtract 3 months and add 1 year). This assumes a 28-day cycle with ovulation on Day 14. For cycles longer or shorter than 28 days, the due date is adjusted accordingly.
Pregnancy Trimesters — What Happens Each Stage
| Trimester | Weeks | Key Developments |
|---|---|---|
| First Trimester | Weeks 1–13 | Embryo forms; heartbeat detectable at week 6; risk of miscarriage highest; morning sickness common |
| Second Trimester | Weeks 14–27 | Baby movements begin; anatomy scan at week 20; gender can be determined; energy often improves |
| Third Trimester | Weeks 28–40 | Rapid growth; lung development; baby positions for birth; Braxton Hicks contractions begin |
Frequently Asked Questions — Pregnancy Due Date Calculator
How accurate is the due date calculator?
The LMP-based due date is an estimate. Only about 5% of babies are born exactly on their EDD. Most births occur within 2 weeks before or after the estimated date. An ultrasound (especially in the first trimester) is more accurate for dating.
What if my cycle is not 28 days?
Naegele's Rule assumes a standard 28-day cycle. If your cycle is shorter or longer, your actual ovulation date differs. A healthcare provider or an ultrasound will adjust the gestational age accordingly.
What is gestational age vs fetal age?
Gestational age counts from the LMP (start of pregnancy by medical convention) and is what this calculator shows. Fetal age (also called conception age) starts from fertilisation — usually 2 weeks later. A doctor always uses gestational age.
What week is considered full term?
Full term is defined as 39–40 weeks of gestation. Early term is 37–38 weeks. Late term is 41 weeks and post-term is 42+ weeks. Babies born before 37 weeks are considered premature (preterm).