Sandpaper Grit Conversion Chart
FEPA P-grades, CAMI/ANSI grit numbers and average particle size in microns, side by side. European paper is marked with a P (FEPA); most US paper carries the bare number (CAMI).
| FEPA (P) | CAMI/ANSI | Particle (µm) |
|---|
Standard: FEPA 43-GB / ISO 6344 / ANSI (CAMI) · Data checked: 2026-10-14
Frequently asked questions
Why does P180 sandpaper feel finer than 180 grit?
Because P-grades and CAMI (US) grit numbers are different scales. FEPA P-grades (the P prefix) and the older CAMI numbers diverge as the grit gets finer, so P180 and CAMI 180 are not the same particle size. Above about P240 the difference is large enough to matter for finishing.
Which way do the numbers run?
Bigger number, finer grit. P24 is very coarse and P2000 is polishing grade. The same is true of CAMI numbers, so a higher number always means finer.
Does the particle size in microns match what I get?
Approximately. The standards set a mean particle size with a permissible spread, and different manufacturers sit at different points within it. Two P180 papers from different brands can feel noticeably different. The micron figure tells you the nominal mean, not a guarantee.
Can I use wet-and-dry paper dry?
You can, but it clogs much faster, especially on paint and soft wood. Its backing and adhesive are designed to tolerate water, and using it wet keeps the abrasive clear and reduces heat, which is why the finish is usually better.