Pregnancy Wheel Calculator

A pregnancy wheel translates a single count -- days elapsed since the first day of the last menstrual period (LMP) -- into the handful of numbers a prenatal visit actually runs on. This calculator takes that day count directly as its input (Days Since LMP), rather than a calendar date -- if you know the calendar date of the LMP, count the days from then to today before entering it here. Gestational Age in weeks is simply that day count divided by 7 and rounded down, so it always rises as Days Since LMP rises across this calculator's full 0-300 day range, never dips back down.

The estimated due date itself comes from Naegele's rule, the standard obstetric convention that adds 280 days (40 weeks) to the LMP; this calculator reports that same 280-day horizon as a countdown -- Days Until EDD and Weeks Until EDD -- rather than a calendar date, and both fall as Days Since LMP rises and reach zero exactly at day 280 (a pregnancy that has run past the estimated due date shows 0, not a negative number). Trimester follows the ACOG Committee Opinion 700 boundaries -- completed weeks 0-13 are the first trimester, 14-27 the second, and 28 onward the third -- and Pregnancy Progress expresses the same day count as a percentage of the full 280-day term, capped at 100% once the due date has passed. None of these figures replace a first-trimester ultrasound, which remains the more accurate way to date a pregnancy when LMP recall is uncertain or cycles are irregular.