健康
预产期计算器
根据末次月经计算预计产期
常见问题
How is a due date calculated?
Most healthcare providers use the first day of your last menstrual period (LMP) and add 280 days (40 weeks) to estimate the due date. This is known as Naegele's rule.
How accurate is the due date?
An estimated due date is just that—an estimate. Only about 4% of babies are born on their actual due date. Most are born between 37 and 42 weeks.
What is my conception date?
Conception typically occurs about two weeks after the first day of your last period, assuming a 28-day cycle.
How to Use the Pregnancy Due Date Calculator
Estimate your due date and track pregnancy milestones from your last period or conception date.
- Enter the first day of your last menstrual period (LMP).
- Adjust your average cycle length if it isn't 28 days.
- See your estimated due date, current week, and trimester.
Due Date Formula
Naegele's Rule
Add 40 weeks to the first day of your last period (adjust for cycle length).
Example:
Input: LMP = Jan 1
Calculation: Jan 1 + 280 days
Result: ≈ Oct 8
Real-World Use Cases
Prenatal Planning
Schedule appointments and prepare for each trimester.
Milestone Tracking
Know your current gestational week.
Tips
Tips
- Only about 4% of babies arrive on the exact due date.
- An early ultrasound gives the most accurate dating.