# The Meaning of D10 D50 D90 in Particle Size Report?

The particle size distribution of powers is typically expressed by these three values. They are often described in academic research reports or quality control reports. "D" means Distribution particle size distribution.

### Small Particle Size

The length unit, D10 represents the 10% of particles in the powders are smaller than this size. Typically, the unit is μm. It can also be represented by a statistical symbols such as DV(0.1) or DV0.1. V means total volume. A laser particle size analyzer does not really measure the particle one by one, but uses laser with different angles, and then retrieve the diffraction patterns from the image sensors. And finally, by performing addition, subtraction, or cross analysis calculations, the instrument determines the statistical proportion of the sizes of particles.

### Big Particle Size

D90 or DV(0.9) means that 90% of the total particles are smaller than this size. Take the report in the article "How To Read The Report of Particle Size Analysis?" for example, D10 is 2.557um, and D90 is 46.88 μm. The two sizes, D10 and D90, enclose the range of particle sizes of the sample powders. The particle size exceeds this range can be ignored, because of the small amount of particles.

### Medium Particle Size

D50 DV(0.5) means that 50% of the total particles are smaller than this size. Or we can say, 50% of the particles are larger than this size. Obviously, D50 is the median particle size distribution, we can call this value, Median. The below figure shows the difference between Median Particle Size and Mean.

The difference between Median size and Mean size

These three values are often calculated as a single value, “Span”. It represents the degree of consistency of the particles in size. D10, D50, D90, and span give you an overall idea of the distribution of particle size.

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