The classic clinician's gestational wheel, online. Enter your due date or last period to see exactly where you sit on the 40-week dial.
It's a circular gestational calculator that clinicians have traditionally used as a paper slide-rule tool — lining up your last period date on an outer ring instantly shows your due date, current week and trimester on an inner scale. This page recreates that same dial digitally.
It's exactly as accurate as any standard due-date estimate — built on Naegele's rule (280 days from the last period), which assumes a typical 28-day cycle with ovulation around day 14. An early ultrasound is generally considered more precise for irregular cycles.
Yes — switch to the "Due date" option above and we'll work backward from it to plot the same position on the wheel, no last-period date required.
Each color marks one trimester: the first third of the dial covers weeks 1–13, the middle covers weeks 14–27, and the final stretch covers weeks 28 through birth around week 40.