Microns

A micron (micrometer, μm) is one-thousandth of a millimeter, and it is the standard unit used in specialty coffee to describe coffee grind particle size with precision. While most home brewers think of grind size in subjective terms like "medium" or "fine," the coffee science community uses microns to quantify and communicate exact particle dimensions.

Typical grind size ranges for common brewing methods are approximately: Turkish coffee at 100–200 microns, espresso at 200–400 microns, pour-over at 400–800 microns, drip at 600–1,000 microns, French press at 800–1,200 microns, and cold brew at 1,000–1,500 microns. These are center-point ranges — any grind also contains a distribution of particles above and below the median.

The particle size distribution — the spread of particle sizes around the median — is as important as the median itself. A grinder that produces a tight distribution (most particles close to the target size) extracts more evenly than one with a wide distribution (many large and small outliers). Laboratory-grade laser diffraction particle analyzers measure these distributions and are used by grinder manufacturers and coffee researchers to evaluate grinder performance.

For most home brewers, micron measurements are academic rather than practical — you adjust grind by taste and by the numbered settings on your grinder rather than measuring particles. However, understanding microns helps when comparing grinders, interpreting reviews, or understanding why a particular grinder performs better for espresso versus filter: the precision and uniformity of particle output at the target micron range is what separates adequate from excellent grinders.