Estimate due date and gestational timeline milestones.
Overview
Pregnancy timeline calculators help estimate due date and current gestational age for planning prenatal milestones. They provide orientation, not definitive clinical dating.
Most due-date estimates use Naegele-style timing from last menstrual period, while conception-based estimates adjust from likely fertilization date.
This calculator helps map trimester boundaries and expected milestone windows, but ultrasound and prenatal care remain the most accurate clinical references.
Steps
Use last menstrual period, conception date, or known due date.
Provide the selected timeline anchor date.
Tool estimates expected delivery and current week/day stage.
See projected first, second, and third trimester ranges.
Use provider assessments for medically validated dating.
Math
Estimated due date approximately LMP + 280 days (or conception date + 266 days)
Obstetric dating typically starts at LMP, roughly two weeks before conception in a standard cycle, yielding a 40-week gestational model.
Worked cases
Add 280 days
Estimated due date around Oct 17, 2026.
Add 266 days
Estimated due date around Oct 25, 2026.
Count elapsed days from LMP
Displays current week/day and trimester status.
Why use this
Questions