The production of bio-based chemicals has received tremendous attention in recent years, but little has been done to understand the broad patterns of the economics of different processes for making these molecules. The diversity of potential chemicals simultaneously makes such an understanding both important and difficult to glean during these early-stages. By using cost correlations and standard scale-factors, a spreadsheet-based early-stage cost estimation tool was developed. The tool, named BioPET (Biorenewables Process Evaluation Tool), allows users to specify up to seven primary unit operations (fermentation, separation, three catalytic stages, and purification), and basic defining inputs for each operation. With these inputs, BioPET computes an estimated minimum selling price for the pathway of interest. Validation of BioPET was conducted by comparing results to literature values and a commercial economic analysis tool for three molecules: ethanol, succinic acid, and adipic acid. BioPET produced virtually identical prices to SuperPro Designer^® for the three chemicals, although the costs were not identically distributed amongst the categories; BioPET produced estimates that were within 40% of other literature values at low feedstock costs, and within 5% at high feedstock costs.