Question about due dates

[Mummy to be x]

Ok so, my question is when calculating your due date on different websites, why is it that some websites ask you how many days your cycle is? When I do this it alters my due date. Why is this?

Thanks for the help ladies.

 

[Rhapsodi]

Because the typical due date calculated by your typical lmp is decided by ovulating at 2 weeks. If you have a shorter or longer cycle then you don't O at day 14 so your due date would be different.

The date calculated with you typical length would be more accurate.

For example my lmp was technically 2/11 but my dr went through my chart and noticed i O day 13 (I think it was even earlier though) so she said to use last lmp as 2/10.