Free Pregnancy Calculator - Estimate Your Due Date
Estimate your due date and track your pregnancy timeline week by week with milestones.
Formula & Methodology
This calculator uses Naegele's Rule, adding 280 days (40 weeks) to the first day of your last menstrual period to estimate your due date and generate a week-by-week pregnancy timeline.
- Due Date = Last Menstrual Period (LMP) + 280 days (40 weeks)
Worked Example
Using the Pregnancy Calculator: apply the formula above to your input values. For instance, Due Date = Last Menstrual Period (LMP) + 280 days (40 weeks). The tool performs each step instantly and shows the result.
Frequently Asked Questions
How is my due date calculated?
It typically adds 280 days (40 weeks) to the first day of your last menstrual period to estimate the due date.
How accurate is a due date?
It is an estimate; only about 1 in 20 babies arrive exactly on the due date, with most within a couple of weeks either side.
What are pregnancy trimesters?
Pregnancy is divided into three trimesters of roughly 13 weeks each, tracking key stages of development.