How is Due Date Calculated?
Most pregnancies last around 40 weeks (or 280 days) from the first day of your last menstrual period (LMP). This calculator uses Naegele's Rule, which is the standard method used by doctors.
What if my cycle isn't 28 days?
The standard calculation assumes a regular 28-day cycle. If your cycle is longer (e.g., 30 days), your ovulation likely occurred later, so your due date is pushed back. Our calculator automatically adjusts for this.