There are some website still applying the traditional design and the design is not fully respond to the different devices. In that case, responsive web design will give a website a greater look, consistent and tailored according to the different devices while browsing without the need to zoom in and all pages suited the screen size. Towards this, the usability assessment is not being used in responsive web design. Thus, five most commonly principles for usability on responsive web design had been identified in the assessment rubric based on analysis of six different e-commerce websites.