How many weeks pregnant am I? How to calculate

Most women get confused about the number of days they have been in pregnancy, especially at the initial stages. It is natural to be excited and anxious to know and keep tabs on each moment of pregnancy. However, there is no way to know exactly when you ovulated and conceived.

This is also the reason even health professionals tend to date pregnancy based on their patient’s LMP (last menstrual period). Hence, it is very crucial to closely monitor your periods and keep a record of it if you have been planning for a baby.

Maintain a diary of your period so that you remember exactly when your last period started. So the first day of your LMP is counted as ‘Day One’ of your pregnancy. Thereafter, use this pregnancy calculator to find out your estimated due date.

First Day of Last Period

Top foods for pregnant women

Most pregnancies tend to last around 40 weeks. Some last for 38 weeks from the date of conception. Hence, the best or most accurate way to estimate your due date is to count 40 weeks, or 280 days, starting from the first day of your last menstrual period (LMP).

Method 2

There is another way to calculate pregnancy. You can subtract 3 months from the first day of your last period. Thereafter, you need to add 7 days to it.

This means if your last period started on April 08, you need to count back 3 months to January 08. Then add 7 days to it which will result as – January 15. This is precisely how your health care practitioner will estimate your due date.

PS: It is quite normal to deliver a week or two before or after.

Date of Conception

Women who have regular menstrual cycle can calculate their due date based on the first day of last period. On the other hand, if your cycle is not regular, this method will not work.

It is crucial to have a reliable estimated date of delivery (EDD). This is how you and your doctor can estimate your conception date. For estimated due date, you need to add 266 days to it.

Irregular Periods/Forgotten Date of Last Period

Ideal nourishment during pregnancy

As already discussed, calculation for the due date works best if your menstrual cycle is regular. This means you need to get your periods every 28 days.

In case, you have an irregular menstrual cycle and you don’t know the date of your LMP, things may get a little difficult. Additionally, if your cycle varies in length, calculating from the day 1 of your LMP may not give you an accurate date.

Ultrasound Scan

This is a good way out when you are unable to determine when you conceived. It also helps when you forget the day of your last menstrual period. An ultrasound can help you and your practitioner determine your due date.

An early ultrasound is important to calculate the due date. The test is recommended if periods are irregular or the patient is 35 years of age or older. Ultrasound is also a crucial step taken by health care practitioners if the patient has a history of miscarriages or complications in pregnancy.

Understanding a Trimester

The literal meaning of a “Trimester” is “3 months”. Most pregnancies last for 9 calendar months. Each pregnancy is categorized into 3 trimesters. This is a simple way to describe changes occurring inside a woman’s body.

  • First Trimester – It typically lasts from the beginning of your pregnancy until you are 13 weeks and 6 days pregnant.
  • Second Trimester – It lasts from 14 weeks to 27 weeks and 6 days of pregnancy. This is also known as the golden period where mother feels better, the bump starts showing, face glows and morning sickness fades off.
  • Third Trimester – The period lasts from 28 weeks of pregnancy until the baby comes out in this world.

How long does a standard pregnancy last?

Healthy diet for healthy pregnancy

Everything depends on the way you count it. A lot of people use this pregnancy calculator to determine their due date by counting forty weeks starting from the first day of their LMP.

Typically, forty weeks adds up to the following:

  • 9 calendar months (30 or 31 days each)


  • 10 lunar months (28 days each)