The actual success or failure of a product is measurable partially in terms of the commercial success of the organization producing it. Addresses how to estimate that success at the concept stage of the design process, prior to detailed design, when there is not yet a physical artefact, and no definite knowledge of how the market will respond to it, but simply some representation of it, for example, design drawings and 3‐D models. Describes a method for approaching this problem by establishing attributes (in “user terms”) which a product must have to enable it to achieve success. Presents an example of a toothbrush, determines the measurable attributes required from this product and describes methods for their evaluation.