How to Calculate Your due Date/EDD in Pregnancy

To calculate the due date/EDD of a pregnancy is quite easy. Pregnancy is a very beautiful thing, and the prayers of many happily married couples. During pregnancy, one of the most common questions usually asked by prospective mothers at antenatal visit is “When am I due?”.

It us important to know your due date so as to enable you plan effectively to be in perfect shape (mentally, financially and otherwise) for the arrival of your baby. Some women would want to know their due date, so that they can know when to leave the country and fly to their country of choice (where they want their child to be a citizen of) for delivery.

calculate due date

It is not only mothers that look for due date, even the fathers are not left out. They would want to know when the bunny is coming out of the Oven, so that they can get their finances & other official engagements in line, so that nothing would disrupt them from welcoming their babies, because, whether you agree or not, men love their babies.

Hence, I would like to use this short post to explain to concerned persons how to calculate their due date. I would try to make this as simple as possible.

Also See:

How to calculate a pregnant woman’s due date/EDD in 3 steps

The due date or Expected Delivery Date(EDD) of a pregnancy is the date that the woman is expected to commence spontaneous onset of labor. This due date for a 28 day cycle is calculated by adding 280 days (9 months and 7 days) to the first day of the last menstrual period (LMP). To do this, you have to;

  1. Know the first day of your last menstrual period (LMP).
  2. Count forward 9 calendar months from that date.
  3. Add 7 days & 1 year to the date. That’s your due date!

See examples below;

  • If your cycle is normal 28 days, your due date or expected date of delivery (EDD) is around 40 completed weeks (i.e. 280 days or 9 months) from the first day you saw blood in your last menstruation (i.e. your last menstrual period, LMP)
  • If your cycle is longer than 28 days, add the difference between your cycle length & 28 days to your calculated date to compensate.
  • If it’s shorter than 28 days, subtract the difference from your calculated date to compensate.

I know this could be a bit confusing, so I would explain more with examples.

Normal 28 day cycle

For example; If your last menstrual period (LMP) was 12th June, 2020. Count 9 calendar months forward from June (which is March!).
Now, Add 7 days & 1 year to the date (which is 12+7=19 & 2020+1=2021, respectively)

So your Expected Delivery Date (EDD) is on the 19th of MARCH, 2021.

Longer Cycle:

However for those whose cycle is more or less than 28 days, you would have to add a little trick to get your due date.
Example: If your cycle usually lasts for 35days, you would need to add the difference, that is (35-28=7). Add 7days to your Calculated Due Date from the normal method, i.e. 7days to 19th March, which becomes 26TH MARCH, 2021.
If your cycle is 32 days, you would add (32-28=4 days), 4 days to the normally calculated one of 19th march, and it would become 23RD MARCH, 2021.

Shorter cycles:

if yours is less than 28 days, you would subtract. That is to say, If you have 21days cycle, subtract the difference (28-21= 7 days). Subtract 7days from your Calculated Due date, i.e. 7days from 19 March, which is 12TH MARCH, 2021.
If it is 23 days, you subtract the difference (28-23=5 days) and then remove it from the normally calculated EDD 19th March, it becomes 14TH MARCH, 2021.

Note that you can deliver once your pregnancy is “term” i.e. anywhere from “37 to 42 weeks.” Most women deliver within this range of time. But people still calculate EDD because most women want a specific date, not a range of time.

NOTE: If the 9 months don’t cross to the next year, you won’t need to add 1 year to your LMP year.

E.g. if LMP is January, EDD will be October of the same year. But if LMP is June, EDD will be March of the next year.

Use Android Application

If you find all these calculations difficult to do, you can simply search on the google app store. There are a number of available android applications that does this easy and fast, and saves you the stress.

You can ask questions in the comment section below and I would try to answer you as early as I can.


  • Nwonye Brian Chidiebube attended the College of Medicine, University of Nigeria Teaching Hospital, UNTH in Ituku Ozalla, Enugu State, Nigeria.

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