Mesh to Micron Conversion Chart: Mesh Size Guide for Milling
Explaining particle size is important when you’re working with powders, whether you are producing absorbents, additives, fillers or materials for downstream blending. Mesh size and micron size are two of the most common ways to describe particle dimensions, and many users search for clear mesh to micron guidance because the two systems don’t always translate intuitively.
What’s the Difference Between Mesh and Microns?
Mesh Size
Mesh refers to the number of openings per linear inch in a screen.
- Higher mesh = smaller openings = finer particles
- Lower mesh = larger openings = coarser particles
A 20‑mesh screen has 20 openings in an inch. A 100‑mesh screen has 100. You can imagine what that means for particle size cuts.
Micron Size
A micron (µm) measures particle diameter directly.
- 1 micron = 0.001 millimeters
- Smaller micron values indicate finer material
Micron measurement is often used when you need precision or tight tolerances.
Rule of Thumb for Quick Conversion
For fast approximations, many engineers use this: Mesh × Microns ≈ 15,000
This isn’t exact, but it’s useful when you need a quick estimate without a full chart. It becomes less reliable at finer mesh counts.
Why Mesh-to-Micron Conversion Matters in Milling
Across industries, particle size impacts flowability, bulk density, reactivity, blending performance, and packaging efficiency. Milling operations rely on accurate mesh or micron targets to deliver repeatable, production ready material.
At M&M Milling, our milling equipment allows us to produce material from coarse grinds to fine, controlled particle sizes. Knowing how mesh and micron measurements relate helps match the milling approach to your downstream needs.
Mesh to Micron Conversion Chart
Below is a commonly accepted reference chart for converting mesh to micron size (approximate). Actual results vary by material characteristics and screen design, but this micron to mesh chart provides a solid guideline.
| U.S. Mesh | Microns (Approx.) | Millimeters |
| 4 | 4760 µm | 4.76 mm |
| 6 | 3360 µm | 3.36 mm |
| 8 | 2380 µm | 2.38 mm |
| 10 | 2000 µm | 2.00 mm |
| 14 | 1410 µm | 1.41 mm |
| 20 | 841 µm | 0.84 mm |
| 30 | 595 µm | 0.60 mm |
| 40 | 400 µm | 0.40 mm |
| 60 | 250 µm | 0.25 mm |
| 80 | 177 µm | 0.18 mm |
| 100 | 149 µm | 0.15 mm |
| 140 | 105 µm | 0.11 mm |
| 200 | 74 µm | 0.07 mm |
| 325 | 44 µm | 0.04 mm |
Note: Mesh values represent average openings. Real world results depend on material hardness, moisture content, and particle shape.
How to Choose the Right Mesh or Micron Size
Mesh tells you the screen opening, but it doesn’t tell you everything about the powder. A sample might pass 40 mesh but still contain some very fine particles unless it’s been classified.
If you’re working with powders that must behave consistently (especially in mixes) you’ll see terms like D10, D50 and D90. These describe how the entire sample is distributed. This approach is standard in applications where consistent performance depends on predictable particle distribution. It basically means someone tracked how much of the sample lands below certain sizes.
Here’s how we generally group mesh ranges:
Coarse Materials (4-20 mesh)
- Ideal for absorbents, carriers, filtration media
- Useful when higher bulk density or stronger flow characteristics are needed
Mid-Range Materials (20-80 mesh)
- Common for fillers, additives, and blends
- Provides uniform distribution without excessive dusting
Fine Materials (80-325 mesh)
- Best for applications requiring tight suspension or precise dispersion
- Supports reactivity and consistency in specialized formulations
When comparing particle cuts, consider how the material must behave in the process. A finer cut does not necessarily improve flow and may compact or bridge depending on humidity, particle shape, and surface characteristics.
If you’re unsure what particle size your formulation needs, our team can help evaluate the best fit.
Explaining “+ / –” Mesh Notation
You may sometimes see particle size ranges written with plus or minus symbols (for example, –100 +200 mesh).
- Negative (–100) means the material passed through a 100‑mesh screen.
- Positive (+200) means the material was retained on a 200‑mesh screen.
So if a supplier says –100 +200, the sample passed the 100 mesh but couldn’t make it through 200 mesh. That means the particles fall somewhere between those two cuts.
Single‑Number vs. Range Mesh Designations
Mesh labels may use either one number or two:
- Single-number mesh (e.g., 60 mesh) generally represents the average or typical particle size cut produced by that screen.
- Two-number mesh (e.g., 30/70 or 20-40 mesh) indicates that all particles fall within that range. Small enough to pass the coarser screen, but too large to pass the finer one.
If you want predictable sizing, the two‑number style helps because it defines what’s above and below the range.
How M&M Milling Achieves Consistent Particle Size
Our powder-handling facilities use a range of toll milling and classification equipment to achieve both mesh and micron-based targets, supporting accurate mesh to micron control during toll processing:
- Air classifying mills for fine, precise particle sizing
- Hammer mills for efficient coarse and mid range grinding
- Screeners + classifiers for dependable particle separation
- Blending + packaging lines that protect material quality from start to finish
Each run is planned around the material, the targets, and what the downstream process needs. If you are unsure which mesh to micron target fits your application, discussing the requirements before sending material can prevent delays and rework.
Ready to Work With M&M Milling?
If you want tighter tolerances, consistent particle size, and a processing partner that helps keep your materials moving, the M&M Milling team is here to help. From milling and particle sizing to blending, packaging, warehousing, transloading, and animal feed additives, we provide end-to-end powder processing services to help out your operations.
Contact our team to learn more about our toll processing services.