Due Date Calculator

Important Note: This tool calculates the due date based on the date of your last menstrual period, and the results are for reference only. Please confirm the final due date with an ultrasound and your doctor's advice.

Based on the last menstrual period date you entered, your expected due date is approximately:

How to calculate your baby's due date?

Once a woman is pregnant, one of the most exciting questions for expectant parents is when the baby will be born. Although we cannot predict the exact day, we can use a scientific method to estimate an approximate due date, which is usually within two weeks of the estimated date.

The calculation method is actually very simple:

You only need to remember two simple formulas:

  1. **Month:** The month of your last menstrual period **minus 3**, or directly **plus 9**.
  2. **Date:** The date of your last menstrual period **plus 7 days**.

**The "minus 3 or plus 9" rule is easy to understand:** If the month of your last menstrual period is January, February, or March, just add 9 directly; if it's from April to December, subtract 3.

**For example:** If the date of your last menstrual period is October 5th, then:

Therefore, your expected due date is approximately July 12th of the following year.

Pregnancy knowledge

Explanation of Due Date Calculation Methods

The due date is mainly calculated using the following methods:

  1. **Last Menstrual Period Method (most common):** The due date is calculated by adding 280 days to the first day of the last menstrual period.
  2. **Simple Calculation Method:** Subtract 3 from (or add 9 to) the month of the last menstrual period, and add 7 days to the date.
  3. **Ultrasound Method:** The due date is estimated based on the size of the fetus during an ultrasound, which is a more accurate method.
  4. **Conception Date Method:** If the date of conception is known, add 266 days to get the due date.
Important Timeframes in Each Stage of Pregnancy
  • **First Trimester (weeks 1-12):** The phase of forming important organs, requiring special care.
  • **Second Trimester (weeks 13-27):** The phase of rapid fetal growth, pay attention to balanced nutrition.
  • **Third Trimester (weeks 28-40):** The phase of fetal maturation, prepare for childbirth.
Tips for Pregnancy Planning
  • Maintain a regular daily routine and get sufficient sleep.
  • Eat a balanced diet and get moderate exercise.
  • Go for regular health checkups to detect problems in time.
  • Avoid contact with harmful substances.
  • Maintain a good mood.
The Importance of Calculating the Due Date

An accurate calculation of the due date is of great significance for prenatal care, scheduling medical checkups, and preparing for childbirth:

  • Helps in formulating a reasonable plan for medical examinations.
  • Helps in understanding the developmental progress of the fetus.
  • Helps in detecting any abnormalities in time.
  • Helps in preparing well for childbirth.
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