We have performed an ab initio study of the oscillation periods of the interlayer coupling in sandwiches of [100] layers of body centered cubic Cr, respectively, Mo, with up to 20 monolayers thickness embedded in an Fe host. Our derived values for the oscillation periods of the interlayer coupling agree well with those expected from the respective Fermi surface calipers and are in excellent agreement with experiment. We compare the interlayer coupling across a nonenhanced paramagnetic Cr spacer with the interlayer coupling across a Cr spacer in the spin-density wave state. We find that the spin-density wave gives rise to an additional contribution to the interlayer coupling. The origin of the observed and calculated 18 \AA{} period of the interlayer coupling can be explained as due to a caliper of the Fermi surface of Cr in the CsCl structure. In the case of the Mo spacer we investigate the influence of the lattice constant on the interlayer coupling and also the dependence of the interlayer coupling amplitude on the Fe magnetic moment.