Pregnancy Calculator
Estimate your due date, pregnancy week, trimester, and important pregnancy dates.
Pregnancy Results
What Is a Pregnancy Calculator?
A Pregnancy Calculator estimates an expected due date based on the first day of the last menstrual period (LMP).
Pregnancy is commonly estimated as approximately 40 weeks from the first day of the last menstrual period.
How to Use the Pregnancy Calculator
- Enter the first day of your last menstrual period.
- Click Calculate Pregnancy.
- View your estimated due date and pregnancy progress.
Pregnancy Trimesters
Pregnancy is commonly divided into three trimesters:
- First Trimester: approximately weeks 1–13.
- Second Trimester: approximately weeks 14–27.
- Third Trimester: approximately week 28 until birth.
The calculator provides an estimate. Actual pregnancy dates can vary, especially when menstrual cycles are irregular or the LMP date is uncertain.
Frequently Asked Questions
How is the estimated due date calculated?
The calculator estimates the due date by adding 280 days, or 40 weeks, to the first day of the last menstrual period.
Is the pregnancy due date exact?
No. The calculated date is an estimate. Only a relatively small proportion of babies are born exactly on their estimated due date.
What if I don't know my last menstrual period?
If you do not know your LMP or your menstrual cycles are irregular, your healthcare provider can help determine pregnancy dating using other information and, when appropriate, ultrasound.
When does the first trimester end?
This calculator uses the end of week 13 as the approximate end of the first trimester.
Can this calculator determine the baby's exact birth date?
No. It provides an estimated due date rather than predicting the exact date of birth.
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