  Consider bond percolation on the square lattice. Let ${\cal C}$ be the
incipient infinite cluster with the incipient measure $\nu$. If a one-arm path
exponent exists and equals $5/48$, it is well known that $E_\nu|{\cal C}\cup
[-n,n]^2| = n^{ 91/48+o(1)}$. In this paper, we focus on the variance of
$|{\cal C}\cup [-n,n]^2|$ and show that $\sigma^2_\nu (|{\cal C}\cup
[-n,n]^2|)= n^{91/24+o(1)}$.

Probability