Sandpaper Grit Conversion Chart: CAMI vs FEPA (P) vs Micron Explained (60–3000 Grit Guide)

Not all sandpaper labels mean the same thing. A U.S. 120 grit isn’t identical to a P120 European sheet, and neither equals a 15-micron polishing film. Understanding how CAMI, FEPA (P-grit), and micron scales align helps you choose the right progression for wood, metal, and resin finishing. Here’s how to build your own grit conversion cheat sheet.

Why Grit Systems Differ

CAMI (Coated Abrasives Manufacturers Institute) is the traditional U.S. scale, measuring average particle diameter. FEPA P-grit uses tighter particle distributions, while micron rating comes from precision polishing films. Converting among them ensures predictable scratch depth and uniform finish quality when switching brands or media types.

Recommended Tools

• Digital caliper or grit reference chart for size checking.
• Sample sheets labeled in CAMI and P grits.
• Magnifier or microscope for scratch pattern comparison.
• Notebook or spreadsheet for tracking equivalents.
• Clean microfiber cloths for handling samples.

Typical Grit Equivalents (Approximate)

• 60 grit (CAMI) ≈ P60 ≈ 265 µm — heavy stock removal.
• 120 grit (CAMI) ≈ P120 ≈ 125 µm — general shaping.
• 220 grit (CAMI) ≈ P240 ≈ 58 µm — pre-finish smoothing.
• 600 grit (CAMI) ≈ P800 ≈ 21 µm — fine finishing.
• 2000 grit (CAMI) ≈ P2500 ≈ 10 µm — polishing prep.
• 3000 grit (CAMI) ≈ P5000 ≈ 5 µm — high-gloss finishing.

Step-by-Step: Building Your Conversion Chart

1. Collect references. Download FEPA and CAMI particle-size tables from manufacturer sites or ISO 6344 standard.
2. Align common grits. Start with base values (60, 80, 120, 220 etc.) and record corresponding micron sizes.
3. Create cross-reference rows. For each grit, list CAMI, FEPA (P), micron, and application examples.
4. Print or digitize. Laminate a small bench-side chart or keep a spreadsheet accessible in your workshop.
5. Test visually. Sand identical material with different-system papers and compare scratch density under raking light.

Special Cases

Above P2500 grit, conversion becomes approximate—film polishing abrasives use micron precision rather than standardized grit numbers. Always check manufacturer data sheets when switching to micro-finishing products.

Pro Tips

• Use one grit system per workflow—mixing CAMI and P numbers without knowing conversion causes grit skips.
• Record preferred jump ratios (roughly 1.6× per step) for efficient scratch removal.
• Mark storage bins with both CAMI and P labels to avoid confusion.

Aftercare

• Keep a printed chart near your sander for quick reference.
• Update conversions when new abrasive lines launch—some brands differ slightly.
• Store sample swatches to feel real texture differences between grit systems.

FAQs

• Is P120 the same as 120 grit? Close, but P120 cuts slightly finer due to narrower particle range.
• Why do micron charts vary? Manufacturers round differently; treat conversions as guidelines, not absolutes.
• Can I mix micron films with sandpaper? Yes — just match approximate particle size (µm) to avoid grit skips.

Watch & Learn

Build your own kit: stock extra-coarse, fine, and super-fine grits in 25-sheet packs to cover the full CAMI ↔ FEPA ↔ micron range for testing and reference.