## Due Date Calculator – How Does Our Due Date Calculator Work?

To calculate when you are most likely to deliver your baby, our due date calculator uses the theory of Naegele’s law. Naegele is a renowned German scientist and according to his findings, a healthy pregnancy lasts approximately 280 days, which roughly translates to 40 weeks.

If you are aged between 25-35 years, you have very high chances of carrying a healthy baby and you therefore stand a higher chance of calculating your expected due date (EDC or EDD) more accurately. According to Naegele’s law, due date calculation starts from the first day of the last menstrual flow or period and you will therefore need to remember this day or date before using the calculator. You will also have to be aware of your average cycle length which you can easily estimate through your last 3-5 cycles.

## Due Date Calculator – Calculation Method 2 (offline)

If you are wondering how doctors calculate due dates so easily and without online calculators, they simply do it by subtracting 3 months from the first day of your last period. They subsequently add one year into this equation and finally add 7 days. This whole calculation gives the due date and month.

### Sample offline calculation (only for a 28 day cycle)

If first day of your last period is 08/10/2013, subtract 3 months to get 05/10/2013.

Add one year to 05/10/2013 to get 05/10/2014

Add 7 days to 05/10/2014 to get 05/17/2014, which is your due date.

## Due Date Calculator – What you can Expect

A due date is not a precise date, but a best guess or an estimation of when birth is likely to happen. Studies show that only 5% of all babies are born at the exact date predicted by due date calculation. Most babies (up to 70%) are born 2-3 weeks later than the due date, while 25% are born one week earlier or later than the predicted date.

## Due Date Calculator – How Different Cycles influence Results

Some of the factors that affect the due date are wrong calculation, especially when a woman cannot remember the precise date of the beginning of her last period, or when she is not aware of her average cycle. Many women have cycles that go below or beyond the average 28 days. Some have cycles that are as short as 21 days and as long as 42 days.

If your cycle is not the average 28 day cycle, no need to panic, you can still use our due date calculator. Just add or subtract the difference in days from the results. If for example your average cycle is 30 days, just add 2 days to the results you get.