Half-plane capacity of a low rectangle

For $R_r=[-r,r]\times (0,1]$ with $r\ge 1$,Indeed, the imaginary part at the Brownian exit point is at most one and the probability of reaching the radius-$O(r)$ neighbourhood containing the rectangle from $iy$ is $O(r/y)$. Consequently $r^{-1}{R}_r=[-1,1]\times (0,r^{-1}]$ has capacity $O(r^{-1})$ although its diameter tends to two.