Calculate your expected delivery date, current pregnancy week, trimester progress, baby development milestones, and important appointment dates — all from your last menstrual period or conception date.
1st Trimester (Weeks 1-12)
Organ formation, morning sickness, fatigue
2nd Trimester (Weeks 13-27)
Baby movement, anatomy scan, energy returns
3rd Trimester (Weeks 28-40)
Rapid growth, Braxton Hicks, nesting
Medical Disclaimer: This calculator provides estimates only. Only about 5% of babies are born on their due date. Consult your healthcare provider for accurate pregnancy dating, especially with irregular cycles or complications.
Pregnancy due dates are most commonly estimated using Naegele's Rule, developed by German obstetrician Franz Naegele in the early 1800s. The formula adds 280 days (40 weeks) to the first day of the last menstrual period (LMP). This assumes a 28-day menstrual cycle with ovulation occurring on day 14.
If calculating from conception date (or IVF transfer date), the due date is 266 days (38 weeks) after conception, since conception typically occurs about 2 weeks after the LMP.
Pregnancy is divided into three trimesters: the first trimester (weeks 1-12) covers early development including organ formation; the second trimester (weeks 13-27) is often called the "golden period" as morning sickness subsides and the baby grows rapidly; the third trimester (weeks 28-40) involves final growth and preparation for birth.
It's important to note that only about 5% of babies are born on their exact due date. Most births occur within a 2-week window around the estimated date. Full-term pregnancy is defined as 39-40 weeks, with early term at 37-38 weeks and late term at 41 weeks. Doctors typically consider inducing labor after 42 weeks.
Disclaimer: This calculator provides estimates only and should not replace professional medical advice. Always consult your healthcare provider for accurate pregnancy dating, especially if your cycles are irregular.