Our calculator uses Naegele's Rule, the standard method used in obstetrics to estimate the due date (EDD).
The formula is based on the assumption that pregnancy lasts approximately 280 days (40 weeks) from the first day of the last menstrual period (LMP):
$$EDD = LMP + 7 \text{ days} - 3 \text{ months} + 1 \text{ year}$$
The standard Naegele's Rule assumes a 28-day cycle. If your cycle is longer or shorter, we add or subtract the difference:
$$Adjustment = \text{Cycle Length} - 28$$
Pregnancy is traditionally divided into three trimesters:
Calculate your estimated due date (EDD) using Naegele's Rule. Track your pregnancy progress and key milestones.
Results are estimates based on standard models. Please verify critical data before taking action. Terms of Use
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