  We derive L\"{u}scher phaseshift formulas for two-particle states in boxes
elongated in one of the dimensions. Such boxes offer a cost-effective way of
varying the relative momentum of the particles. Boosted states in the elongated
direction, which allow wider access to energies, are also considered. The
formulas for the various scenarios (moving and zero-momentum states in cubic
and elongated boxes) are compared and relations between them are clarified. The
results are applicable to a wide set of meson-meson and meson-baryon elastic
scattering processes, with the two-particle system having equal or unequal
masses.
