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Calculate your Due Date

Your due date is calculated by adding 280 days (40 weeks) to the first day

of your last menstrual period (assuming a 28 day cycle).

Even if you don't have a 28 day cycle, most calculators let you put the cycle

length more than 28 days and up to 45 days. This will give you an

approximate due date. However, if you are not sure of your last menstrual

date or your cycle length is highly irregular, don't worry.

Because, your first scan will surely give you an exact due date based on

the fetus development.

What is the last menstrual period (LMP)?

The LMP is your last menstrual period. It is the first day that your last

menstrual cycle began. That is the date you use when entering the LMP.

Note that your menstrual period and ovulation are counted as the first two

weeks of pregnancy. If you deliver on your due date, your baby is actually

only 38 weeks old, not 40.

What is the difference between an online conception

calculator and the “wheel” conception calculator that a doctor


There is no difference between the two. The doctor uses the first day of

your last menstrual cycle to estimate due date and conception date in much

the same way the online conception calculator works.

All results are based on the input, so you need to know the accurate first

day of their last menstrual cycle to achieve the best and most reliable


Please remember that your due date is only an estimate. Every pregnancy

is unique and your baby will come when it's ready. Be sure to talk to your

health care provider about your due date.

On average only 5% of births take place exactly on the estimated due date.

Most are born within a week either side of the estimated due date. A

normal pregnancy can last anywhere between 38 and 42 weeks.

Keep reading our blogs! We are open to feedback and suggestions!

-Guest Author on

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