Is foreigncredits.com a reliable website for converting one's grade in another country to GPA?

I am currently residing in Canada and I am quite confused as the grading scale here is
90-100=A+
80-89=A
70-79=B
60-69=C
50-59=D
while the American GPA is completely different.
I have an average of around 90 with a few ups and downs. Foreigncredits.com said my GPA is 4.0 while the American grading scale puts me at a way lower GPA. I am moving to America this year and I am quite concerned about this.
(P.S I am currently a sophomore)
Thanks!

Will you be attending high school in the US? Then the high school where you study will decide how to convert your grades.

Are you applying to college? Then the places you apply to will decide how to interpret your grades.