As an estimation program of U.S. Environmental Protection Agency’s EPI Suite™, KOWWIN™ estimates the log octanol-water partition coefficient, log KOW, of chemicals using an atom/fragment contribution method. The chemical structure must be entered as a SMILES notation (there is a 100 character limit for this demo) or CAS number. To run the KOWWIN program, download the EPI Suite program from the U.S. Environmental Protection Agency website.