LMP dating
Sample
Last period start date
What you get
Gestational age summary and trimester context (educational).
Pregnancy Calculator
Obstetric dating is confirmed by ultrasound in care. This tool uses a standard menstrual dating rule.
Pregnancy Calculator
YearMonthDay
Due date (280d rule)
Mar 8, 2026
Gestational age
~67 weeks
Trimester
3
These tools provide general fitness estimates only and are not a substitute for professional medical advice.
How to Use This Tool
- Enter the first day of the last menstrual period.
- Review EDD and approximate gestational age.
- See your clinician for dating and care.
Features
- 280-day Naegele-style EDD from LMP
- Trimester label
- Educational only
Example
Frequently Asked Questions
How is due date estimated?
From last menstrual period we apply a common 280-day (40-week) rule and derive gestational weeks/trimester. Ultrasound dating from your clinician takes priority.
Is this medical advice?
No. This calculator is for general education and planning only. Always consult a qualified clinician for personal health decisions.
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