Pregnancy calculator...?

Question

I think I'm having a duuuh moment. I've used two different calculators and they are giving different results. How do you calculate your due date?

Answer

Thanks for your input :-)

Answer

They went off the first day of my last period so they have me at 4 weeks even though I only ovulated on February 10th.

Answer

My mom gave me 3 dates (she's so excited she can't stand herself lol) - 1 based on first day of last period,  1 based on conception date (that was an awkward convo), and 1 I think she made up. No idea what that third was based on. I think just counting 39 weeks after my first pee stick positive?

Answer

I think Dr's go from the first day of your last period, even though im sure i conceived on the 4th and my period started Jan 27th.  They go back to the beginning of your cycle  and mark that as the start of your first trimester. So somehow even though we were early testers we somehow got to cheat the system and already made it through our 1st month of Pregnancy :) (technology)

Answer

No idea how it works, maybe one calculating from the first day of your period and the other basing it off the last day?