What Is D50 Particle Size?

D50 (also written as d50 or D₅₀) is the median particle size of a material, defined as the particle diameter at which 50% of the sample mass is smaller and 50% is larger. It is the single most commonly reported metric for characterizing the central tendency of a particle size distribution. When a supplier says their product has a "D50 of 200 microns," they mean half the material by weight is finer than 200 microns and half is coarser. D50 is determined from sieve analysis data, laser diffraction, or other particle sizing methods.

D50 is part of the broader "Dx" notation system where "x" represents any cumulative percentage point. D10 and D90 describe the finer and coarser ends of the distribution, respectively. Together, D10, D50, and D90 provide a concise three-number summary of any particle size distribution. This notation is used across all industries that process bulk solids, including food, pharmaceuticals, chemicals, minerals, plastics, and metal powders.

D50 Values for Common Screening Applications

Why This Matters in Vibratory Screening

D50 is the most commonly specified particle size metric in purchase orders, product specifications, and quality certificates. Understanding D50 is essential for selecting the right screen and evaluating screener performance.

• Screen size selection — The D50 of your feed material relative to your target mesh size determines the proportion of near-size particles, which is the primary factor in screening efficiency and blinding risk. When D50 is close to your screen opening, expect slower throughput and more frequent de-blinding.
• Product specification — Many customers specify acceptable D50 ranges in their purchasing requirements. Your vibratory screener must maintain the product within that D50 window, which requires the correct mesh size and consistent screening conditions.
• Process monitoring — Tracking D50 over time via routine sieve analysis reveals shifts in your incoming material or production process. A rising D50 in your fines fraction could indicate a worn screen or decreasing screening efficiency.
• Equipment sizing — D50 data helps determine the screener diameter and deck configuration needed for a given application. A ScreenerKing SiftPro or SiftPro 48 can be specified with the correct screen and feed rate based on D50 and distribution data.

Related Glossary Terms

• D10, D90 — Distribution spread measurements at the 10th and 90th percentiles
• Sieve Analysis — The test method used to determine D50 from screen data
• Mesh Size — The screen opening specification related to D50 values
• Screening Efficiency — Performance metric influenced by D50 relative to screen opening
• Blinding — Screen clogging that occurs when D50 is near the screen opening

D50 Particle Size FAQs

What does D50 mean in particle sizing?

D50 is the median particle diameter — the size at which exactly 50% of the sample's mass consists of particles smaller than that value and 50% consists of particles larger. For example, a D50 of 200 microns means half the material by weight is finer than 200 microns and half is coarser.

How is D50 determined from sieve analysis?

D50 is calculated by plotting the cumulative percentage passing against sieve opening size from a sieve analysis and interpolating the particle size at the 50% passing point. If 45% passes a 100 mesh sieve (149 microns) and 62% passes a 60 mesh sieve (250 microns), the D50 falls between 149 and 250 microns and is found by interpolation on the cumulative distribution curve.