Equilibrium binary liquid mixture below its upper critical consolute temperature, confined between opposing walls, is investigated by molecular dynamics simulations. The wall potentials are chosen strong enough to ensure that both walls are wet and therefore the interface is delocalized. The interfacial widths (W) are determined from density profiles and from order parameter profiles for a series of wall to wall distances (D). Early saturation of the width with increasing D is found already for D similar to 20 sigma and data at the other end are consistent with the theoretical prediction of linear dependence of W-2 on D. Also, the error function complement is found slightly superior to the hyperbolic tangent, on the basis of a new test of consistency proposed.