The Ionic Strength Calculator helps you determine the ionic strength III of a solution using the formula I=12∑cizi2I = \tfrac{1}{2}\sum c_i z_i^2I=21​∑ci​zi2​, where cic_ici​ is the molar concentration of each ion and ziz_izi​ its charge. You can add any number of ionic species (entering concentration in M or mM and the ionic charge) and the tool computes the total ionic strength, shows each ion’s contribution, and reports values in both M and mM. Optionally, it can estimate activity coefficients using the Davies equation (valid roughly up to I≈0.5I \approx 0.5I≈0.5 M), giving approximate γ\gammaγ values for each ion. This calculator is ideal for solution preparation, equilibrium calculations, and teaching—useful for chemists, students, and lab technicians.