Sauter mean diameter

Sauter mean diameter (or SMD) is a way to measure how small particles are. It’s like a game of “bigger, smaller.” To find the SMD, you compare the sizes of particles in a group and see which one is the smallest and which one is the biggest. The SMD is the average size between the smallest and the biggest particle. To calculate it you take the sum of all of the diameters of the particles divided by the number of particles. That is the SMD.