Estimate child due dates based on Last Menstrual Period (LMP) dates.
Calculator Parameters
Enter details and click calculate to view the results instantly.
Calculation Examples
Scenario Inputs
Output Result
lmp : 2026-01-01
Estimated Due Date: October 8, 2026
About Pregnancy Due Date Calculator
Pregnancy Due Date Estimator. Estimate child due dates based on Last Menstrual Period (LMP) dates. Starlightopia provides this tool completely free and online, optimized for instant, accurate computations.
Technical Specifications
CategoryHealth
Target ValueEstimated Due Date
Inputs Required (1)
Date of Last Menstrual Period (date)
Frequently Asked Questions
What is Naegele's rule for pregnancy calculation?
Naegele's rule estimates a pregnancy due date by adding one year, subtracting three months, and adding seven days to the first day of your last menstrual period.
How many weeks does a standard full-term pregnancy last?
A normal full-term pregnancy lasts approximately 40 weeks, which equates to 280 days from the start of the last period.
What percentage of babies are born exactly on their estimated due date?
Only about 4% to 5% of babies arrive precisely on their estimated due date, with most arriving within two weeks before or after.
Can an early ultrasound shift my original due date estimate?
Yes, a first-trimester crown-rump length ultrasound measurement provides highly accurate dating that can update your due date.
How are the three trimesters of pregnancy divided?
The first trimester runs from week 1 to 12, the second from week 13 to 27, and the third spans from week 28 until birth.