Spatial averaging filter involves smoothing noise images into non-noise images, which is a feature that has significantly impacted many portable devices in recent years, including Tablet PC, E-book reader, and mobile camera phones. Given the limited memory space and the computational power of portable devices, reducing the space and computational complexity of an embedded system is of priority concern. This work presents an efficient algorithm for spatial averaging filter with less computational complexity. Less auxiliary memory is applied to avoid re-compute the sum and to retain the sum between rows. Experimental results demonstrate that the proposed method is faster than other comparison methods in time complexity. Moreover, the proposed algorithm can be run in personal digital products due to its simplicity and efficiency.