Magnetron sputter deposition onto a rotating drum is a method applied to high-throughput large-area optical coating deposition, where film physical thickness uniformity is an important parameter. Techniques have been developed, such as masking/substrate movement, in order to improve sputtered film uniformity. In this study, a model is described and validated for predicting film uniformity. Experimental data show excellent agreement with modeled simulations, with and without a modified sputtering mask. Practical application is demonstrated in maximizing uniformity over an individual substrate size of 100 cm2 for a high-optical-density visible/near-infrared dual-band laser protection filter.