Pregnancy Due Date Calculator

Pregnancy Due Date Calculator. Find out when your baby would be born

Are you pregnant and do not know when your delivery date is? The online pregnancy due date calculator is here to help you.

The pregnancy due date is an estimate of when a pregnant woman will give birth. A pregnancy due date calculator is an online tool that helps expecting parents count the date of delivery.

The pregnancy due date calculator uses specific information to estimate the likely date when the baby is due. Remember, this is just an estimate; individual factors can influence the actual date.

The pregnancy due date calculator is helpful for parents to plan for the arrival of their baby and for healthcare providers to monitor the pregnancy.

What is a pregnancy due date calculator and what does it calculate?

The pregnancy due date calculator is a tool designed to estimate a pregnant woman’s expected delivery date. It calculates the due date based on the first day of the woman’s last menstrual period and the average period cycle length.

The due date calculator assumes a standard 40-week pregnancy, counting from the first day of the last menstrual period. The calculator takes these inputs and applies a formula to estimate when a woman will likely give birth.

However, remember that the pregnancy due date calculator gives an estimated date, and variations can influence the timing of childbirth. Healthcare professionals may also use other methods, like ultrasound, to refine the prediction based on the baby’s development.

What are the units used in the pregnancy due date calculator?

The pregnancy due date calculator typically uses weeks or days as the unit of measurement. The first day of the woman’s last menstrual period determines the estimated due date in weeks or days.

On average, pregnancy lasts 267 days or 38-40 weeks. If the woman is sure of the conception date, she can add 267 days to it to know her estimated date.

So, when you use the pregnancy due date calculator, the result will often be presented as a certain number of weeks or days after the start of the last menstrual period.

How do you use the pregnancy due date calculator?

Every month, a mature ovarian follicle in a woman’s ovary ruptures and releases an ovum (egg). An ovum is a critical cell for reproduction.

When a sperm fertilizes the ovum and the fertilized egg implants in the uterus, it results in conception. The fertile period, when birth is possible, is typically a few days around ovulation.

Ovulation occurs around fourteen days before the first day of the next menstrual cycle, and a woman is considered fertile for four days before ovulation, the day of ovulation, and one day after ovulation. Ovulation calendars and calculators are commonly used to identify the fertile period for conception.

Regular cycles facilitate accurate prediction, but irregular cycles may need alternate methods like basal body temperature, Luteinizing Hormone (LH) strips, cervical mucus consistency, or ovulation studies. The ovulation calculator helps predict the fertile window if the menstrual cycle is regular.

The formulae that can estimate your expected due dates are:

Date of the first day of the woman’s last bleed + 281 days = Estimated date of delivery


Date of the first day of the woman’s last period + 7 days – 3 months = Due date in the following year

These formulae are based on the 28-day menstrual cycle.

Due Date Calculation

Last Menstrual Period: (MM/DD/YYYY format)
Average Length of Cycles: (22 to 45) (defaults to 28)
Average Luteal Phase Length: (9 to 16) (defaults to 14)
Estimated Conception:
Estimated Due Date:
Estimated Fetal Age:

The pregnancy due date calculator values

The pregnancy due date, also known as the estimated due date, is the anticipated date when a pregnant woman is likely to give birth. The calculations are based on the first day of her last menstrual period and the average length of her menstrual cycle.

The standard calculation assumes a 38-40-week pregnancy, but it is important to note that only about 5% of the women deliver on their due date.

The pregnancy can be categorized into three stages, referred to as trimesters. A trimester lasts between 12 and 14 weeks, and the pregnancy lasts between 38 and 40 weeks.

Trimester Number of weeks
1st 0-13
2nd 14-26
3rd 27-40

It should be noted that during each trimester, a woman will have her own unique experiences, and the fetus will meet specific development milestones.

The pregnancy due date serves as a reference point for monitoring the progress of pregnancy and planning for childbirth. The healthcare providers may use additional information, such as ultrasound reports, to refine the estimate.

Health implications

When the pregnancy lasts for 40 weeks of the gestational period, the baby and the mother have no health complications if no problems are encountered. Health implications occur when the gestational period is less than 40 weeks or more.

Premature Birth (Before 37 weeks)

Post-term Birth (After 42 weeks)

A pregnancy due date calculator helps to predict when a baby will arrive. It is a handy tool for planning, but it is always best to stay in touch with the doctor for the most reliable information during pregnancy.