I agree with the comment above, with all three of my pregnancies I did the same, & Dr confirmed & my due date has never changed with either child.
To get the best accurate results, put in the first day of your last period (lmp) & it's best to know the length of your cycle. Just a example of my current pregnancy..
My lmp was Feb 18th 2016,
I have a 28 day cycle
We conceived March 3rd 2016
Positive pregnancy test March 17th 2016
And due date is Nov 24th 2016
Hope this helps!!
Yes. When I got a positive home pregnancy test, I calculated my due date with a conception calculator and when my doctor told me my due date at my first appointment it was the same
Thank you so much ladies this is really helpful to me and i appreciate you took your time to explain (: Thank you