Solid-state batteries hold the promise to be highly impactful next-generation technologies for high-energy and -power-density rechargeable battery applications. It is crucial to identify the metrics that an emerging battery technology should fulfill to achieve parity with conventional Li-ion batteries, primarily in terms of energy density. However, limited approaches exist today to assess and extrapolate the impact of battery designs and choices of cell components on the cell-level energy density of a solid-state battery. Herein, we introduce the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), an interactive experimental toolkit to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and costs and in utilizing inverse engineering concepts to correlate the cell energy density output to materials and cell design inputs.