Due Date Calculator
Estimate your due date from the last menstrual period (LMP).
Input Data
Lmp Year
1–12.
1–31.
Results
Estimated due date (YYYYMMDD).
20,261,008
Due date and current week.
預產期 ≈ 2026-10-08；目前約 35 週（估算，以超聲波為準）。
At a glance:Due date = LMP + 280 days (Naegele's rule); current week = (today − LMP) ÷ 7. Complements period and bmi.
Formula
due date = LMP + 280 days.
week = (today − LMP) ÷ 7.
How to Use
- Enter the first day of your last period.
- The tool gives the due date and current week.
Case Studies
LMP 2026-01-01 → due 2026-10-08
1/1 + 280 days ≈ 10/8.
FAQ
Is it accurate?
It is an estimate; ultrasound is more precise.
How is it different from period?
Period estimates the cycle; this estimates the due date.
What is it used for?
Prenatal visit planning.
How precise?
To the date, plus the week to one decimal.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.