Health
Due Date Calculator
Estimate your baby's due date from your last menstrual period (LMP).
Default 28 days. Adjust if your cycle is longer or shorter.
Estimated Due Date
Gestational Age
Trimester
LMPDue date
Week 0Week 20Week 40
Key Dates
Medical disclaimer: This calculator provides an estimate only using Naegele's Rule. Actual due dates vary. Consult your healthcare provider for accurate dating, which may use ultrasound measurements.
Trimester Overview
1st Trimester
Weeks 1–12Organ formation. Morning sickness common. NT scan at ~week 12.
2nd Trimester
Weeks 13–27Growth phase. Anatomy scan at ~week 20. Baby begins moving.
3rd Trimester
Weeks 28–40Rapid weight gain. Lung maturation. Full term at week 37.
Pregnancy Milestones
| Week | Milestone |
|---|---|
| 4 | Missed period |
| 6 | Heartbeat detectable by ultrasound |
| 10 | End of embryonic period |
| 12 | End of 1st trimester · NT scan |
| 16 | Sex may be visible on ultrasound |
| 20 | Anatomy scan · halfway point |
| 24 | Viability milestone |
| 28 | 3rd trimester begins |
| 37 | Full term |
| 40 | Estimated due date |
| 42 | Post-term |
Naegele's Rule
The standard formula for estimating due date:
EDD = LMP + 280 days
Assumes 28-day cycle and ovulation on day 14. For longer/shorter cycles, ovulation day shifts accordingly, adjusting the EDD.