CAMI vs FEPA

Why the same number is not the same paper

CAMI is published by the Coated Abrasive Manufacturers Institute and is the system you see on American sandpaper: 80, 120, 220. FEPA is the Federation of European Producers of Abrasives and its numbers carry a P prefix: P80, P120, P220. Both count abrasive particles, but they count them under slightly different rules and grade the particle size into slightly different ranges.

At coarse grits the two track each other closely, which is why nobody notices. By the fine end they have drifted: FEPA P1200 is finer than CAMI 1200, and the gap widens as the numbers climb. That is why an American 400-grit sheet can feel coarser than a European P400, and why finishing schedules built on one scale do not transfer cleanly to the other.

The micron figure is the only universal number. It describes the average particle diameter in micrometres, and it means the same thing in Ohio as in Osaka. If you are matching paper across brands or continents, convert to microns and compare those.

Where the practical gaps are

The mismatch that bites most often is around 220 — the standard final grit before finish. CAMI 220 averages about 68 microns; FEPA P220 sits close to it but is not identical. If a finish behaves differently after switching paper brands from different countries, this is usually why.

The second is in automotive work, where schedules are written in P-grades but paper is often bought in CAMI. A primer sanded at "P400" and then at "400" are two slightly different surfaces, and on a clear coat that difference shows.

Which system should you buy in?

Buy the system that matches the paper you can actually get. If your local supplier stocks CAMI, work in CAMI and convert only when a project or a product specifies otherwise. Mixing the two inside one project is where mistakes creep in — a schedule written as P400, P800, P1200 performed with CAMI 400, 800, 1200 will not produce the same finish because each step removes slightly less than intended.

The systems also differ in how tightly they grade the particle size. FEPA grades into narrower bands, which is why European paper from different manufacturers behaves more consistently than American paper at the same number. If consistency across brands matters — automotive work, production finishing — the P-grades are the safer specification.

For wood, none of this matters much. The differences at 80, 120 and 180 are small enough that technique dominates. For paint, metal and plastic, where you are chasing a scratch you cannot see, the numbers matter and microns are the honest unit.

Questions people ask