Its not completely white

I've always interpreted it as white, since it's a sign of her magic and Anna has a white streak. But I gues you could argue for either one.

So many color debates: Cinderella's white/blue/silver dress, Anna's blonde/red/strawberry blonde/ginger hair, Elsa's blonde/white hair, That ugly dress that went viral....
Anyway, I've always seen her as a blonde. It looks different from Anna's white streaks.

I've seen platinum blonde hair and I've seen white hair but I can honestly say that Elsa is in NO WAY platinum blonde. Her hair is as white as snow! If she's a platinum blonde than Ariel's hair is pink. Elsa's hair is the same shade as Anna's white hair when she gets struck.

Her hair is white. I've seen people with platinum blond hair in real life, and Elsa's hair does not any way resemble that color.

White-blonde, aka Platinum:

link
link
link

compare it to Anna's white hair and it's definitely yellower.

link
link

but yeah, it's canon that it's only this color because of the magic.

its easier to say white idk