| Milestone | Week | Date | Status |
|---|
The standard method for calculating your due date is Naegele's Rule, based on the first day of your Last Menstrual Period (LMP).
Due dates are estimates — only about 5% of babies are born on their exact due date. A healthy full-term pregnancy is between 37–42 weeks. Always consult your healthcare provider for personalized medical guidance.
If your LMP (Last Menstrual Period) began on January 15, 2025: using Naegele's Rule, add 9 months → October 15, 2025, then add 7 days → due date: October 22, 2025. Alternatively: January 15 + 280 days = October 22, 2025. Your current gestational age on April 16, 2025 would be 13 weeks and 1 day — the start of your second trimester.
Pregnancy is described as 40 weeks because the clock starts from your Last Menstrual Period, not from conception. Ovulation and conception actually occur approximately 14 days after the LMP — meaning gestational weeks 1 and 2 occur before pregnancy technically begins. Doctors use LMP-based dating because it is an observable event (unlike the exact moment of conception), making it a reliable, standardized reference point.
Disclaimer: This calculator provides estimates for planning purposes only. Due dates are not medical certainties. Always work with your OB/GYN or midwife for personalized prenatal care and accurate dating.
This free pregnancy due date calculator estimates your baby's due date, tracks your current pregnancy week, and identifies your trimester based on your last menstrual period (LMP). Using Naegele's Rule — the standard used by OB/GYN professionals — it adds 280 days (40 weeks) to the first day of your last period to calculate your estimated due date with accuracy.
Beyond just the due date, the calculator shows key pregnancy milestones and trimester dates so you can plan prenatal appointments, maternity leave, and your birth plan. Whether you just found out you are pregnant or are comparing your dates with those from an ultrasound, this pregnancy calculator is a useful and reassuring reference tool throughout your pregnancy journey.
Using Naegele's Rule: add 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP). Equivalently, add 9 months and 7 days to your LMP. For example, LMP of January 15 → due date October 22. This assumes a 28-day cycle; the calculator adjusts for longer or shorter cycles.
Only about 5% of babies are born on their exact due date. A healthy full-term pregnancy spans 37–42 weeks. An early ultrasound (before 12 weeks) is the most accurate way to confirm gestational age and may revise the due date if your LMP is uncertain. The LMP method is reliable when cycles are regular.
Gestational age is counted from the first day of the LMP — it is what doctors use. Fetal age (embryonic age) is counted from conception, which occurs approximately 2 weeks after the LMP. So gestational week 10 = fetal week 8. All prenatal care milestones are described in gestational weeks.
The first trimester ends at the end of week 12 (the beginning of week 13). After 12 weeks, the risk of miscarriage drops dramatically — from approximately 10–20% to under 2%. Most couples choose to announce their pregnancy publicly after this milestone.
The anatomy scan (20-week scan or mid-pregnancy ultrasound) is performed between weeks 18 and 22, most commonly at 20 weeks. It checks fetal anatomy, organ development, placenta position, amniotic fluid levels, and cervical length. Gender can be determined at this scan if you choose to know.
Yes. If you know your conception date, your due date is approximately 266 days (38 weeks) later. If you have had an early dating ultrasound, the sonographer's estimated due date is typically more accurate than the LMP method and will be used by your care team as the official reference.
Irregular cycles make LMP-based dating less reliable, since ovulation may occur at a different time than assumed. An early ultrasound between 6 and 12 weeks is the most accurate dating method for irregular cycles. Our calculator allows you to adjust your cycle length to improve the estimate.
Start prenatal vitamins with at least 0.4 mg (400 mcg) of folic acid — ideally before conception and certainly by week 6 to support neural tube development. Book your first prenatal appointment before 12 weeks. Avoid alcohol, raw fish, unpasteurized cheeses, and high-mercury fish. Discuss any medications with your doctor. Morning sickness (nausea) is extremely common and usually improves by week 12–14.