Due Date Calculator — Pregnancy Week Calculator
Calculate your baby's due date and track pregnancy weeks and trimesters.
About Due Date Calculator
The Due Date Calculator estimates your baby's due date based on the first day of your last menstrual period (LMP) or conception date. It calculates your current pregnancy week, trimester, and provides a timeline of important pregnancy milestones.
This calculator uses the standard 280-day (40-week) pregnancy duration from the first day of your last period. It shows you how far along you are, when you'll enter each trimester, and your estimated delivery date. Remember that only about 5% of babies arrive exactly on their due date.
How to Use Due Date Calculator
- Select your calculation method (last period or conception date).
- Enter the date of your last menstrual period or conception.
- Click 'Calculate Due Date' to see results.
- Review your due date, current week, and trimester.
- Track pregnancy milestones and important dates.
Key Features
Calculate estimated due date
Show current pregnancy week
Identify current trimester
Timeline of trimester milestones
Days until due date countdown
Conception date option
Instant calculations
100% private and secure
Frequently Asked Questions
How accurate is the due date calculator?
The calculator provides an estimated due date based on the first day of your last period. Only about 5% of babies are born exactly on their due date. Most babies arrive within 2 weeks before or after the estimated date.
How is the due date calculated?
The due date is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14.
What if I don't know my last period date?
If you know your conception date, the calculator can work from that. Alternatively, an early pregnancy ultrasound (6-10 weeks) can provide the most accurate dating based on fetal measurements.
When do the trimesters start and end?
First trimester: weeks 1-12, Second trimester: weeks 13-26, Third trimester: weeks 27-40. Each trimester marks different developmental stages and physical changes for mother and baby.
Can my due date change?
Your due date may be adjusted after an early ultrasound if fetal measurements suggest a different conception date. After 20 weeks, dates are rarely changed as measurements vary more between babies.