What is Pregnancy Due Date Calculator?
A pregnancy due date calculator estimates your baby's expected arrival date (EDD — Estimated Date of Delivery). Knowing your due date helps you plan prenatal care, prepare for birth, and track your baby's development week by week.
Our calculator supports three methods: Last Menstrual Period (LMP), Ultrasound dating, and IVF transfer date. It displays a trimester progress bar, key milestone dates, and a complete timeline from conception to post-term.
How It Works
Choose your calculation method. For LMP: enter the first day of your last period — the calculator adds 280 days. For ultrasound: enter the scan date and gestational age at that time. For IVF: enter the transfer date and embryo day (3 or 5). The calculator shows your due date, current week, trimester progress, and upcoming milestones.
Formula
LMP Method: Due Date = LMP + 280 days Ultrasound: Due Date = Scan Date − Days at Scan + 280 IVF Day 5: Due Date = Transfer Date − 19 + 280 IVF Day 3: Due Date = Transfer Date − 17 + 280
Formula Explained
Naegele's rule adds 280 days (40 weeks) from the LMP, assuming ovulation occurs on day 14 of a 28-day cycle. For irregular cycles, ultrasound dating is preferred. IVF calculations work backward from the transfer date to an equivalent LMP date. The gestational age includes the ~2 weeks before conception, which is why pregnancy is "40 weeks" even though fertilization occurs around week 2.
Example
LMP: January 1, 2025 Due Date: October 8, 2025 (280 days later) Current date: April 8, 2025 Gestational age: 13 weeks + 5 days Trimester: Second Progress: 35%
Tips & Best Practices
- ✓First-trimester ultrasound (6-13 weeks) provides the most accurate dating.
- ✓If your periods are irregular, tell your provider — LMP dating may be less accurate.
- ✓The due date is an estimate — prepare for birth anytime from 37-42 weeks.
- ✓Download a pregnancy tracking app to follow week-by-week development.
- ✓Most providers recommend 10-15 prenatal visits during pregnancy.
Common Use Cases
- •Determining your estimated due date for prenatal planning
- •Tracking pregnancy progress week by week
- •Planning maternity/paternity leave dates
- •Scheduling prenatal appointments and tests
- •Understanding fetal development milestones