Pregnancy Due Date Calculator — Accurate EDD, LMP & Conception Date EstimatorNaegele's Rule · EDD · Gestational Age · Trimesters · Weeks Pregnant · Conception Window
Use this free Pregnancy Due Date Calculator to instantly estimate your Estimated Due Date (EDD), calculate how many weeks pregnant you are, and track your complete pregnancy timeline and milestones— based on either your Last Menstrual Period (LMP) or known conception date. Using the clinically standard Naegele's Rule: EDD = LMP + 280 days (40 weeks / 9 months + 7 days)— the same formula used by obstetricians, midwives, and gynecologists worldwide — this pregnancy calculator instantly computes: 🤰 Estimated Due Date (EDD) · 📅 current gestational age in weeks and days · 🌸 estimated conception date and fertile window · 📊 trimester breakdown — 1st, 2nd & 3rd trimester dates · 🌟 key pregnancy milestones and development weeks.
This online pregnancy due date calculator supports all major pregnancy dating methods: LMP-based due date calculation (Naegele's Rule), conception date-based EDD estimation, IVF transfer date due date calculation (3-day and 5-day embryo transfer), and ultrasound dating cross-reference by crown-rump length (CRL). Track all critical pregnancy week milestones including Week 6 — first heartbeat detectable, Week 12 — end of first trimester and nuchal translucency scan, Week 20 — anomaly scan (mid-pregnancy ultrasound), Week 28 — third trimester begins, and Week 40 — full term due date. A full-term pregnancy is 40 weeks (280 days) from LMP — though normal delivery ranges from 37–42 weeks. Trusted by expectant mothers, partners, midwives, and obstetric healthcare professionals for accurate pregnancy planning and antenatal care scheduling.
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Pregnancy Due Date Calculator — Estimated Delivery Date and Gestational Age Week by Week
The standard method for calculating estimated due date (EDD) uses Naegele's Rule: add 280 days (40 weeks) to the first day of the last menstrual period (LMP). This assumes a 28-day cycle with ovulation on day 14 — an approximation that works for average cycles but can be several days off for women with cycles consistently shorter or longer than 28 days. The pregnancy due date calculator applies Naegele's Rule as the standard baseline and optionally adjusts for non-28-day cycles, adding or subtracting the difference from the 14-day ovulation assumption.
Gestational age is counted from the LMP, not from conception, which is 2 weeks later. So a woman who is "6 weeks pregnant" conceived approximately 4 weeks ago. This dating convention means gestational weeks 1-2 technically predate conception. Ultrasound dating in the first trimester (crown-rump length measurement at 8-12 weeks) is more accurate than LMP-based dating when cycles are irregular and often produces a slightly different EDD than Naegele's Rule. If ultrasound and LMP dates differ by more than 5-7 days, the ultrasound date typically takes precedence.
Trimester milestones and key development markers fall at specific gestational ages: fetal heartbeat detectable at 6-7 weeks, NT scan at 11-14 weeks, anatomy scan at 18-22 weeks, viability threshold at 22-24 weeks, full term at 39-40 weeks. The calculator displays all key gestational milestones as calendar dates from the entered LMP, turning the abstract 40-week timeline into a concrete schedule of appointments and developmental checkpoints.