Systems and methods can determine product lines product searches. One or more computing devices can receive a product query of search terms. The product query may be classified to identify a product category. A brand may be identified for the product query. The brand may be selected from a list of known brands for the product category. One or more unknown product line terms may be identified within the product query. A metric may be computed to indicate how well the unknown product line terms correspond to an actual product line within the brand. The metric may be compared to a specified threshold. The unknown product line terms may be designated as a new product line of the brand if the metric favorably compares to the specified threshold. A product search may be performed on the product query. Product search results may be returned according to the product search.