Xbox Game Pass Ultimate

I had previously taken advantage of the $1 upgrade deal to Game Pass Ultimate in September of last year and I just bought Xbox live gold for 12 months and I want to upgrade. But when I go into the store it gives me the $1 option to upgrade, will this give
me the conversion rate which is about 4 months or the full 12?. And if not, is there a way to convert the full 12 months of gold into ultimate?

:)