VitalMetricHubDue date calculator
Naegele’s rule adds 280 days (40 weeks) to the first day of your last menstrual period. Dating scans may adjust your official due date.
Age notice (18+)
Fertility and pregnancy tools on VitalMetricHub are intended for adults. They are not a substitute for care from an obstetrician, midwife, or other licensed clinician.
VitalMetricHub does not knowingly collect personal information from children under 13 (COPPA). These tools are not directed at minors.
Go deeper
Evidence-informed guides tied to this calculator — still educational, not personal medical advice.
How this calculator works
Open any section below for the underlying method, how to read your results, practical tips, and limits. This site is for education only—not medical advice or a personal care plan.
Formula and method
From LMP: due date ≈ first day of LMP + 280 days (40 weeks). From conception: due date ≈ conception date + 266 days.
These rules assume a 28-day cycle with ovulation around day 14; real cycles differ.
How to read your result
Your output is an educational estimate of delivery timing, not a scheduled delivery date.
Clinicians often set an “official” due date after early ultrasound, especially if cycles are irregular or LMP is uncertain. Weeks-along counts here are also approximate.
Practical tips
Use the first day of bleeding of your last period, not spotting alone, unless your clinician instructs otherwise.
If you conceived with IVF or know transfer dates, your clinic will use specialized dating—prefer their numbers.
IOM weight-gain ranges on this page are general education; twins, complications, and personal plans need clinician-specific guidance.
Limitations
This tool cannot detect pregnancy complications, fetal growth issues, or replace prenatal care.
For any bleeding, severe pain, or emergency symptoms, seek immediate in-person care—not an online calculator.
Sources, formulas & further reading
Based on: Naegele’s rule (LMP + 280 days) and conception + 266 days (educational dating only).
For additional clinical context, see independent references from the publishers below (WHO, CDC, PubMed, Medscape, ACE, ACOG, NIH, NCBI, USDA — as applicable).
Medical disclaimer
This tool is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult your doctor or qualified healthcare professional before making any health-related decisions. Results are estimates only.
Last medically reviewed: March 2026
Content last updated: March 30, 2026