What is Z-Average size?

The Z-Average size (or mean), also known as the cumulants mean (‘harmonic intensity averaged particle diameter’), is the central and most stable parameter produced and the best value to report when used in a quality-control setting as it is defined in ISO 13321. This is a hydrodynamic parameter and only applicable to particles in dispersion or molecules in solution. Z-Average mean size can be sensitive to even small changes in the sample and will only compare with the size measured by other techniques if your sample is mono-modal, spherical or near-spherical in shape, very narrow and prepared in a suitable dispersant.