For educational and reference use only. These calculators do not replace clinical judgement, local protocols, or a qualified clinician. Verify every result independently before it informs patient care.
Women's & obstetric imaging
EDD & Gestational Age (LMP)
Estimated due date and today’s gestational age from the first day of the last menstrual period (Naegele’s rule), assuming a regular 28-day cycle.
Assumes a regular 28-day cycle.
Result
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Enter all values to calculate.
Formula
EDD = LMP + 280 days. Gestational age = today − LMP.
Disclaimer
LMP dating is unreliable with irregular cycles, recent contraception, or uncertain dates. First-trimester ultrasound (CRL) is the most accurate dating method.
For educational and reference use only. These calculators do not replace clinical judgement, local protocols, or a qualified clinician. Verify every result independently before it informs patient care.
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