A method for estimating the relative impact of two or more patent portfolios belonging to one or more companies is disclosed. Each patent of a patent portfolio is categorized into at least one market segment. A Technological Strength Index (TSI) is computed for each patent based on patent citations. An Economic Impact Index (EII) value is computed for each market segment based on the market size and market growth rate of the market segment, and the market share of the company in each market segment. A Company Innovation Efficiency Index (CIEI) value is computed for the patent portfolio based on the R&D expenditure of the company and the number of patents granted to the company. TSI and EII values of patents in a patent portfolio, and the CIEI value of the patent portfolio are used to compute an Overall Index for the patent portfolio. A similar exercise is carried out for all the portfolios being analyzed. The Overall Index provides a relative measure of the impact of the patent portfolios.