Pregnancy Calculator
Due date, conception and trimester from last menstrual period.
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About this calculator
Naegele's rule assumes ovulation day 14 of a 28-day cycle. Longer/shorter cycles shift the estimate linearly — this calculator applies that correction.
Formula
EDD = LMP + 280 days + (cycle−28); conception ≈ LMP+14+(cycle−28).
Health metrics are informational estimates and are not a medical diagnosis.
Frequently Asked Questions
How accurate is EDD?
Only ~5% deliver exactly on EDD; ±2 weeks is considered term. Ultrasound dating refines it.