Pregnancy Due Date Calculator
Estimate your due date, conception window, pregnancy week, trimester, and key pregnancy milestones from your last period date.
| Milestone | Approx Week | Date | Notes |
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Pregnancy Due Dates and Milestones Explained
A pregnancy due date calculator estimates the expected delivery date based on the first day of the last menstrual period or a known conception date. The most common pregnancy dating method counts approximately 40 weeks from the last period date, because ovulation and conception usually happen around two weeks after that date in a typical 28-day cycle.
The result is an estimate, not a guarantee. Only a small percentage of babies are born exactly on their due date, and healthcare providers may adjust dates after an ultrasound, cycle history, fertility treatment records, or medical review.
This calculator also shows estimated conception timing, current pregnancy week, trimester, days remaining, and a milestone timeline so the date is easier to understand in practical pregnancy planning.
How the date is estimated
For last-period dating, the calculator adds 280 days to the first day of the last menstrual period and adjusts for cycle length. A longer cycle usually shifts ovulation later, while a shorter cycle may shift it earlier.
Conception window
Conception timing is estimated around ovulation, but real timing can vary. Sperm can survive for several days and ovulation may shift due to stress, illness, cycle irregularity, postpartum changes, or medication.
Trimester tracking
Pregnancy is commonly split into three trimesters. The calculator uses gestational age to show the likely trimester and current week, which can help organize appointments and planning.
Medical guidance matters
This tool is for general education and planning. A healthcare professional may use ultrasound measurements, fertility treatment dates, or clinical history to confirm or update your official due date.