Pregnancy Due Date Calculator
Easily determine your estimated due date, see how far along you are, and track the milestones of your pregnancy.
Milestones (Estimates)
Weight Gain Guidelines
Note: Only about 5% of babies are born exactly on their estimated due date. Normal pregnancies can last anywhere from 38 to 42 weeks.
🏆 Tracking Your Timeline
Everything you need to know about using this calculator and the math behind it.
How it Works
Estimates the expected due date (EDD) of a baby based on the first day of the last menstrual period (LMP) or ultrasound measurements.
The Formula
Naegele's rule: EDD = LMP + 7 days - 3 months.
Pro Tip
Remember that only about 4% of babies are born exactly on their due date. It's completely normal to deliver anywhere between 37 and 42 weeks.
Frequently Asked Questions
How is my due date calculated? +
The standard due date calculation uses Nägele's Rule: add one year to the first day of your last menstrual period (LMP), subtract 3 months, and add 7 days. This equals 280 days (40 weeks) from the LMP, assuming a 28-day cycle with ovulation on day 14. For irregular cycles, ultrasound dating is more accurate. Your healthcare provider may adjust the due date based on first-trimester ultrasound measurements.
What happens at each trimester? +
First trimester (weeks 1–13): organ formation, highest miscarriage risk, morning sickness common. Second trimester (weeks 14–26): rapid growth, baby begins moving, energy often improves. Third trimester (weeks 27–40): major weight gain for baby, lung maturation, preparation for birth. The 20-week anatomy scan and glucose screening around week 24–28 are routine milestones most providers schedule.
When is the baby's gender typically detectable? +
Genetic sex can be determined as early as 10 weeks via cell-free DNA (cfDNA) blood tests, or through chorionic villus sampling (CVS) at 10–13 weeks. Ultrasound can typically reveal sex around 18–20 weeks during the anatomy scan, though the baby's position affects accuracy. Non-invasive prenatal testing (NIPT) available around week 10 screens for chromosomal conditions and can also reveal sex.
What's the difference between gestational age and fetal age? +
Gestational age is counted from the first day of the last menstrual period (LMP), which is the medical standard. Fetal age (or embryonic age) is counted from conception, typically 2 weeks less than gestational age. When doctors say "you are 8 weeks pregnant," they mean 8 weeks gestational — the embryo is actually about 6 weeks old. Gestational age is used universally for due date calculations and prenatal milestones.
What is a "full-term" vs. "preterm" birth? +
Full-term is 39–40 weeks 6 days. Early term: 37–38 weeks 6 days. Late preterm: 34–36 weeks 6 days. Very preterm: 28–31 weeks. Extremely preterm: under 28 weeks. Babies born at 37+ weeks are considered viable with standard care; those born earlier may face respiratory, feeding, and developmental challenges. "Full term" was formerly defined as 37+ weeks, but was updated to 39+ weeks to reflect better outcomes from allowing additional maturation time.