Pregnancy Calculator

Tool Guide

About the Due Date Calculator

The pregnancy / due date calculator is an online pregnancy timing tool. Just enter the first day of your last menstrual period, and the system automatically calculates your due date.

The due date calculator can also estimate your current pregnancy stage, gestational weeks and days, prenatal check-up registration time, time remaining until the due date, and more, making it suitable for pregnant women, doctors, and families planning a pregnancy.

It uses the standard 280-day / 40-week pregnancy algorithm (counted from the first day of the last menstrual period) to quickly and accurately estimate the baby's birth date.

How to Estimate the Due Date from the Last Menstrual Period

Step 1: Enter the date of your last menstrual period (the first day of menstruation is recommended);

Step 2: The system automatically calculates the due date, current gestational weeks, pregnancy progress, prenatal check-up registration time, and more;

Step 3: You can take a screenshot to save it for easy sharing and recording.

Due Date Calculator FAQ

How is the due date calculated?

The due date is usually counted as 280 days (40 weeks) from the first day of the last menstrual period, i.e. adding 9 months and 7 days. For example, if the last menstrual period was January 1, the due date is around October 8.

Why use the last menstrual period for estimation?

Most women do not know the exact date of ovulation or conception, but the last menstrual period is a definite, easy-to-recall point in time, so this method is commonly used in medicine for estimation.

Is the due date accurate?

The due date is an estimated time; actual delivery usually occurs 1-2 weeks earlier or later. Only about 5% of pregnant women deliver on the exact due date.

Who is it suitable for?

People who are planning a pregnancy and want to estimate the timing; expectant mothers who are already pregnant and want to check their current gestational weeks; and doctors or midwives who use it to quickly estimate gestational age and progress.