Pregnancy Due Date Calculator interactive tool
Calculator
Enter the first day of your last menstrual period (LMP). The due date is estimated using Naegele's rule (40 weeks from LMP). Only a healthcare provider can confirm your due date.
Result
Wed, Oct 22, 2025
175 days ago
~65 weeks along (if LMP is correct)
What Is Pregnancy Due Date?
A pregnancy due date calculator provides an estimated timeline for when your baby is likely to be born. While only about 5% of babies are born exactly on their predicted due date, having an accurate estimate is essential for monitoring fetal development and planning for your new arrival.
How is the Due Date Calculated?
Most medical professionals and calculators (including this one) use a standard formula known as Naegele's Rule. This formula assumes a standard 28-day menstrual cycle and a 40-week gestation period.
- Step 1: Identify the first day of your Last Menstrual Period (LMP).
- Step 2: Add one year to that date.
- Step 3: Subtract three months.
- Step 4: Add seven days.
When to Consult a Doctor
This calculator provides a highly accurate mathematical estimate, but your healthcare provider may adjust your official due date later during your pregnancy based on early ultrasound measurements, which can track the physical size of the fetus more precisely.
How To Use the Pregnancy Due Date Calculator
- Enter the first day of your last menstrual period (LMP) in the input field.
- The pregnancy due date calculator will instantly display your estimated due date, based on Naegele's rule.
- Use the Example button to load a sample LMP date, or Reset to clear all fields for a new calculation.
- Remember that due dates are estimates; your healthcare provider may adjust it with early ultrasound results.