Pregnancy Due Date Calculator | Estimated Timeline
Estimate pregnancy due date, current week, trimester, and key timeline dates from last menstrual period and average cycle length.
Estimated Pregnancy Timeline
Estimate Pregnancy Due Date from LMP
Enter the first day of the last menstrual period and average cycle length to estimate due date, current pregnancy week, trimester, and full-term timing.
Due Dates Are Medical Estimates
Cycle length, ovulation timing, ultrasound dating, and medical history can change the official due date. Confirm pregnancy dates with a qualified healthcare professional.
About This Tool
Due Date Calculator estimates a pregnancy due date from the first day of the last menstrual period or from a known conception date. It also shows key pregnancy milestones and trimester boundaries week by week.
When to Use It
Use this after a positive pregnancy test to estimate the due date before the first ultrasound, when planning maternity leave around an expected delivery, or when tracking weekly pregnancy milestones.
How to Use
- Enter the first day of your last menstrual period.
- Alternatively enter a known conception date.
- Click Calculate to see the estimated due date.
- Review the trimester timeline and key milestones by week.
Frequently Asked Questions
How accurate is an LMP-based due date?
The LMP method assumes a 28-day cycle and ovulation on day 14. A first-trimester ultrasound provides a more accurate estimate based on foetal measurements.
How many weeks is a full-term pregnancy?
A full-term pregnancy is 39 to 40 weeks from the last menstrual period. Births between 37 and 42 weeks are considered term.
What is Naegele's rule?
Naegele's rule calculates the due date by adding one year, subtracting three months, and adding seven days to the first day of the last period — equivalent to adding 280 days.