  Mass formulas for multicenter BPS 4D black holes are presented. For example,
ADM mass for a two center BPS solution can be related to the intercencenter
distance $r$, the angular momentum $J^2$, the dyonic charge vectors $q_i$ and
the value of the scalar moduli at infinity ($z_\infty$)by $M_{ADM}^2 =A\left
(1+ \alpha J^2\left(1+\frac{2M_{ADM}}{r}+\frac{A}{r^2}\right)\right)$ where
$A(Q),\alpha(q_i)$ are symplectic invariant quantities ($Q$, the total charge
vector) depending on the special geometry prepotential defining the theory. The
formula predicts the existence of a continuos class, for fixed value of the
charges, of BH's with interdistances $r\in (0,\infty)$ and $M_{ADM}\in
(\infty,M_\infty)$. Smarr-like expressions incorporating the intercenter
distance are obtained from it: $$ dM\equiv\Omega d J+\Phi_i d q_i+ F dr,$$ in
addition to an effective angular velocity $\Omega$ and electromagnetic
potentials $\Phi_i$, the equation allows to define an effective "force", $F$,
acting between the centers. This effective force is always negative: at
infinity we recover the familiar Newton law $F\sim 1/r^2$ while at short
distances $F\sim f_0+f_1/r^2$. Similar results can be easily obtained for more
general models and number of centers.
