Strategic product planning is a challenging entrepreneurial task. It supplies input to product design and development and creates a business plan for profitability. One of the strategic product planning considerations is whether to develop a single product line or a product family consisting of several product variants. However at present, there are not many quantitative tools to determine whether to pursue the single product line option or a product family option. This paper proposes a four-force model that describes the factors influencing the product planning decision. Using the four-force framework, a neural network model has been developed to help strategic product planning.