Health
Due Date Calculator
Last updated: July 11, 2026
Calculate your estimated due date (EDD) based on your last menstrual period (LMP) or conception date. See your pregnancy timeline and milestones.
How to Use This Due Date Calculator
- Choose your calculation method: Last Menstrual Period (LMP) or Conception Date.
- Enter the appropriate date.
- Click "Calculate Due Date" to see your estimated due date and pregnancy progress.
Due Date Formula
From LMP: EDD = LMP + 280 days (40 weeks)
From Conception: EDD = Conception Date + 266 days (38 weeks)
Naegele's rule: Add 7 days to LMP, subtract 3 months, add 1 year.
Pregnancy Trimesters
| Trimester | Weeks | Duration |
|---|---|---|
| First Trimester | Week 1 – 12 | 12 weeks |
| Second Trimester | Week 13 – 26 | 14 weeks |
| Third Trimester | Week 27 – 40 | 14 weeks |
Examples
Example: LMP Method
LMP = January 1, 2026:
EDD = January 1 + 280 days = October 8, 2026
Frequently Asked Questions
How accurate is the due date?
Only about 5% of babies are born on their exact due date. The EDD is an estimate, and normal pregnancies can range from 37 to 42 weeks. Your healthcare provider may adjust the date based on ultrasound measurements.
What if I don't know my LMP?
If your LMP is uncertain, an early ultrasound can help determine gestational age. You can also use the conception date method if you know when ovulation occurred. Your healthcare provider can help determine the most accurate dating method.