Answer:
12
Explanation:
there is a middle square of 2×2 complete units.
then there is 1 complete unit in every of the 4 directions connected to that central square.
and then we have in every direction 2 half-units connected to them.
they are half units, because the line through them is exactly their diagonal.
so, in sum, we have
2×2 + 4×1 + 4×(2/2) = 4 + 4 + 4 = 12