This study presents a first-order thermal analysis for electric double layer capacitors (EDLCs). It is based on the lumped-capacitance approximation and accounts for both irreversible and reversible internal heat generation. A simple analytical expression for the overall temperature rise during galvanostatic cycling was derived. A scaling analysis was performed and demonstrated with experimental data collected from commercial EDLCs. This thermal model enables rapid estimation of reversible heat generation and prediction of the temperature evolution in EDLCs without performing computationally intensive numerical simulations.