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Health
Due Date
Estimated due date from last menstrual period
Runs locally in your browser
Parameters
Results
- Gestational week
- 8
- Days until due date
- 220
- Trimester
- 1
Enter the number of days since the first day of your last menstrual period.
How it works
Estimates gestational age and due date from the first day of the last menstrual period (LMP).
Who it's for: Expectant parents tracking pregnancy week-by-week before or between prenatal visits.
Uses Naegele's rule: due date = LMP + 280 days (40 weeks).
Calculates current gestational week and days remaining until due date.
Assigns trimester (1, 2, or 3) based on gestational week.
How to use
- Count days from the first day of your last menstrual period to today.
- Enter that count in Days since LMP.
- Read Gestational week — matches how OB/GYNs often date pregnancies before ultrasound adjustment.
- Check Days until due date for countdown planning.
- Note Trimester for understanding fetal development milestones.
- Confirm dating with your provider — early ultrasound may revise the due date by several days.
Good to know
- Only about 4–5% of babies arrive on the exact due date — full term spans roughly 37–42 weeks.
- Irregular cycles make LMP dating less reliable; first-trimester ultrasound is the gold standard.