conception date due date calculator
Conception Date to Due Date Calculation Guide
When conception date is known, due-date estimation can use a direct day-count method. This article explains the exact process.
How to calculate using Pregnancy Due Date Calculator
- Choose method: LMP-based or conception-date-based estimation.
- Enter date and cycle length when using LMP mode.
- Use output as planning estimate and confirm with clinical care.
Pregnancy Due Date Calculator formula
- LMP method: due date ≈ LMP + 280 days (adjusted by cycle length).
- Conception method: due date ≈ conception date + 266 days.
- Pregnancy week estimate uses days elapsed against 40-week baseline.
Worked example
- If LMP is Jan 1 with 28-day cycle, due date is around early October.
- For conception-date method, add 266 days directly.
- Compare with scan-based estimate during prenatal care.
Accuracy and interpretation notes
- This is not a medical diagnosis tool.
- Ultrasound dating may adjust estimated due date.
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