The Kw Calculator determines the ionization constant of water or the concentration of hydrogen or hydroxide ions depending on the values provided. It uses the formula Kw=[H+]×[OH−]K_w = [\mathrm{H^+}] \times [\mathrm{OH^-}]Kw​=[H+]×[OH−], which represents the equilibrium constant for the self-ionization of water. By entering any two of the three quantities — [H+],[OH−][\mathrm{H^+}], [\mathrm{OH^-}][H+],[OH−], or KwK_wKw​ — the calculator instantly finds the missing one. This tool is useful for chemistry students and professionals studying pH, pOH, and water equilibrium relationships, especially at different temperatures where KwK_wKw​ changes slightly.