An Estimated Due Date (EDD) calculates the approximate 40-week (280-day) mark of pregnancy measured from the first day of your last menstrual period (LMP).
Halfway point! Baby can swallow and may suck its thumb.
Key Pregnancy Milestones & Appointments
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Week 4: Implantation & Positive Test
May 8, 2026
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Week 6: Heartbeat Detectable
May 22, 2026
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Week 10: First Prenatal Visit
Jun 19, 2026
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Week 12: End of 1st Trimester
Jul 3, 2026
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Week 16: Prenatal Screening (Quad Test)
Jul 31, 2026
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Week 18: Anatomy Scan & First Kicks
Aug 14, 2026
24
Week 24: Age of ViabilityNEXT
Sep 25, 2026
27
Week 27: End of 2nd Trimester
Oct 16, 2026
28
Week 28: Glucose Tolerance Test
Oct 23, 2026
32
Week 32: Growth Ultrasound
Nov 20, 2026
36
Week 36: Group B Strep Test
Dec 18, 2026
37
Week 37: Early Full Term
Dec 25, 2026
40
Week 40: Estimated Due Date
Jan 15, 2027
Recommended Pregnancy Weight Gain
Based on IOM (Institute of Medicine) guidelines. Enter your pre-pregnancy measurements.
Medical Disclaimer: Estimates are calculated using standard clinical formulas (Naegele's rule for LMP, 266 days post-conception, IVF transfer offsets). Always confirm due date with your OB/GYN or midwife.
Affiliate disclosure: links above may earn us a commission — this never affects the calculation results above.
⚕️MEDICAL & YMYL DISCLAIMERReviewed August 2026
Educational Purpose Only: The calculations, formulas, and estimates provided by this pregnancy & obstetrics calculator are intended solely for educational, research, and informational purposes. They do not constitute medical advice, diagnosis, or personalized treatment plans.
Always consult a qualified healthcare professional, physician, or registered dietitian before making changes to your diet, exercise regimen, calorie intake, or pregnancy care plan. Never disregard or delay professional medical advice because of something you read on this website.
SCIENTIFIC FORMULA & METHODOLOGY
Naegele’s Rule (Standard Obstetric Method)
EDD = LMP + 1 Year - 3 Months + 7 Days
(For standard 28-day menstrual cycle)
First described by German obstetrician Franz Karl Naegele, this clinical rule assumes a 28-day cycle with ovulation occurring on day 14.
Clinical Limitations & Considerations
Only 4% of babies are born on their exact estimated due date. Full-term delivery normally occurs anywhere between 37 weeks (early term) and 41 weeks + 6 days. First-trimester ultrasound dating (CRL measurement) supersedes LMP dating if there is a discrepancy of >5 days.
Scientific References & Literature
ACOG Committee Opinion No. 700 (2017). "Methods for Estimating the Due Date." Obstetrics & Gynecology, 129(5), e150-e154.
Mongelli, M., et al. (1996). "Estimating the date of delivery: ultrasonographic versus menstrual date calculation." Lancet, 348(9033), 978.
Frequently Asked Questions
How accurate is a due date calculator?
LMP-based calculators provide an accurate baseline estimate. Obstetricians confirm or adjust your official EDD during your first prenatal crown-rump length (CRL) ultrasound scan.
How many weeks is a full-term pregnancy?
Full-term pregnancy is defined as 39 weeks 0 days through 40 weeks 6 days by the American College of Obstetricians and Gynecologists (ACOG).