Calculating home office square footage?

[Steve Legnaioli]

my house measures 1522 ft.² overall, I rent out 430 ft.² of that, I have a 10 x 10 home office also in the house, in order to calculate the percentage for the home office, do I include the total square footage of the house, or just the square footage of the house where I live in, minus the 430 I rent out?

thanks