Pregnancy Calculator

Pregnancy Calculator – Quick Cheat Sheet

Inputs: LMP (first day of last period), optional Cycle length (defaults 28), and optional As of date (defaults to today, UTC).
EDD: LMP + 280 days + (cycle − 28).
Gestational age: computed from LMP, shifted by (cycle − 28) days; reported as weeks + days.
Trimester rule: 1st = 0–13w6d; 2nd = 14–27w6d; 3rd = 28w+.
Milestones shown: 12w, 20w, 28w, 37w (early term), 40w (EDD), 41w (post-term check).
Cycle adjustment: Longer cycles tend to ovulate later → later EDD; shorter cycles → earlier EDD.
Reminder: This is an estimate; actual dating may be refined by ultrasound and your provider.

Edge cases & notes

Negative GA means the As of date precedes the effective conception window (preconception planning).
All calculations use strict YYYY-MM-DD in UTC to avoid DST/locale issues.
You can set As of in the future to see projected GA and days to EDD.