CAMI versus P-Grit Numbering: What the Labels Mean

What CAMI and P-grit mean

CAMI and P-grit are two standards for classifying abrasive particles in sandpaper. CAMI refers to the US grading system associated with the Coated Abrasives Manufacturers Institute. P-grit refers to the FEPA grading system for coated abrasives; its grades use a P prefix, as in P120.

In either system, a higher number generally means finer abrasive. But the number is a grade within a standard—not a measurement you can compare perfectly across every brand and product.

Are CAMI and P-grit numbers equivalent?

Often, common grades with the same number are close enough for practical sanding decisions. For example, CAMI 80 and P80 are broadly similar starting points. That does not mean the systems are identical or that every matching number will produce exactly the same surface.

The standards classify particle sizes and distributions differently, and products can vary by manufacturer and abrasive type. Treat cross-system comparisons as a guide, not a precise conversion. If a finish or product calls for a specific standard, follow that specification.

These are broad comparisons, not a promise of exact equivalence. Check the package for the grading system, especially when switching brands or following a finishing schedule.

How to choose when switching systems

• Use the same grit number as a starting point when moving between CAMI and P-grit. At common grades, it is usually a reasonable approximation.
• Follow the finish or coating instructions if they specify a grit and standard. Sanding too coarsely can leave scratches; sanding too finely can reduce adhesion for some coatings.
• Keep the abrasive sequence consistent. Move through progressively finer grits and remove the scratches from the previous step before advancing. A large jump can leave visible marks behind.
• Check the abrasive format and backing, too. A matching grit number does not make a sheet, disc, sponge, or mesh product otherwise interchangeable for every tool or task.

For wood, test the final grit on an inconspicuous area when the surface will be stained or finished. The wood species, coating, and sanding method can affect how scratches show.

The practical takeaway

CAMI and P-grit are different numbering standards, but matching numbers are often close enough to guide an ordinary grit choice. Use the P prefix to identify FEPA grades, treat crosswalks as approximate, and prioritize the product or finish maker’s specified grit when the result depends on it.