The variation of entanglement density with interface width at an interface between two polymers is calculated using the relationships between chain packing and entanglement. The chain packing is obtained by the use of self-consistent mean-field techniques to calculate the average chain conformations within the interface region. The interface width is controlled by an assumed value of Flory-Huggins interaction parameter chi between the two polymers. As the value of chi is increased from 0 (completely miscible) to 0.1 (immiscible with a sharp interface), the calculated entanglement density is found to decrease by about a factor of 2. These modified entanglement densities are used within an existing model of interface coupling to estimate the effect of entanglement changes on the variation of interface toughness with interface width.