UK and European sandpaper uses FEPA P-grades (P120, P240…); US paper often uses CAMI numbers without the P. The two match closely up to about 220 grit, but finer than that a P-grade is finer than the same CAMI number: P400 is roughly CAMI 320, and P1200 is roughly CAMI 600.
The first table converts between the two systems with approximate particle sizes. The second gives a grit sequence for common hobby materials, from shaping to finish, and says when to sand wet. Further down are polishing compounds and abrasive types. Search any grit or material, or filter the grit table by range.
FEPA P-Grade vs CAMI Grit Conversion
| FEPA P-grade | Avg. particle (µm) | Nearest CAMI | CAMI particle (µm) | Class | Typical use |
|---|---|---|---|---|---|
| P24 | ~764 | 24 | ~708 | Extra coarse | Stripping paint and heavy stock removal with a floor or belt sander. Leaves deep scratches. |
| P40 | ~425 | 40 | – | Extra coarse | Levelling rough boards, removing old finish, shaping. Belt sanders and flap discs on metal. |
| P60 | ~260–269 | 60 | ~268 | Coarse | Fast shaping, flattening glue-ups and epoxy pours, cleaning welds with flap discs. |
| P80 | ~197–201 | 80 | ~192 | Coarse | First sanding of rough-sawn or planed timber with marks; removing layer lines on large prints. |
| P100 | ~156–162 | 100 | ~141 | Medium | Removing planer and machine marks. Common first grit on a random orbital sander. |
| P120 | ~125–127 | 120 | ~116 | Medium | General wood prep; key for paint; first grit on 3D prints with visible layer lines. |
| P150 | ~97–100 | 150 | ~93 | Medium | Refining after P120; a good final grit for oak and ash before oil or stain. |
| P180 | ~78–82 | 180 | ~78 | Fine | Final sanding of most hardwoods before finish; sanding primer on wood. |
| P220 | ~65–68 | 220 | ~66 | Fine | Final grit for close-grained wood and MDF before paint; light sanding between coats. |
| P240 | ~58.5 | 220–240 | ~53.5 | Fine | Between coats of varnish or lacquer; sanding filler primer on prints. |
| P280 | ~52.2–52.5 | 240 | ~53.5 | Very fine | Flatting between finish coats; prepping primer for top coat. |
| P320 | ~46.2 | 280 | ~44 | Very fine | Between coats; first wet grit on cured epoxy and resin prints. |
| P400 | ~35 | 320 | ~36 | Very fine | Wet sanding primer and paint; smoothing epoxy and resin prints. |
| P500 | ~30.2 | 360 | ~28.8 | Very fine | Wet sanding paint and clear coat before polishing. |
| P600 | ~25.8 | 400 | ~23.6 | Very fine | Wet sanding paint, epoxy and acrylic edges; satin finish on metal. |
| P800 | ~21.8 | 400–500 | ~19.7–23.6 | Extra fine | Wet sanding toward a polish on epoxy, resin, acrylic and paint. |
| P1000 | ~18.3 | 500 | ~19.7 | Extra fine | Removing orange peel in clear coat; pre-polish on metal and resin. |
| P1200 | ~15.3 | 600 | ~16 | Extra fine | Last grit before compound on many jobs. |
| P1500 | ~12.6 | 800 | ~12.2 | Ultra fine | Final wet sanding of clear coat and epoxy before polishing compound. |
| P2000 | ~10.3 | 1000 | ~9.2 | Ultra fine | Final wet sanding before a fine polish; headlight and acrylic restoration. |
| P2500 | ~8.4 | 1200 | ~6.5 | Ultra fine | Very last paper step before polish on show finishes. |
| P3000 and finer | maker-specific | – | – | Polishing papers / pads | Foam-backed pads and polishing papers; sizes are set by each maker rather than the FEPA P table. |
Particle sizes are approximate average values; published tables differ slightly, which is why some are given as a range. “Nearest CAMI” is matched by particle size. Makers grade and round differently, so treat conversions as a guide.
Grit Sequence by Material
| Material | Shape / remove | Smooth | Final before finish | Between coats / to polish | Wet or dry | Notes |
|---|---|---|---|---|---|---|
| Softwood (pine, spruce, cedar) | P80 | P120 | P150–P180 | P240–P320 | Dry | Going finer than P180 can burnish softwood so stain takes unevenly. Sand with the grain. |
| Hardwood (oak, ash, walnut, maple) | P80–P100 | P120–P150 | P180 (P220 for maple, cherry) | P320–P400 | Dry | Open-grain oak and ash: stop at P150–P180 so oil and stain can soak in. Do not skip more than one grit. |
| MDF and plywood faces | – | P120 | P180–P220 | P240–P320 on primer | Dry | Plywood face veneer is very thin: never start coarser than P120. Seal MDF edges before paint. |
| Mild steel (rust, mill scale, welds) | P40–P60 flap disc | P80–P120 | P180–P240 for paint | P400+ for a brushed look | Dry | Wear eye and hand protection. Remove all dust and oil before paint. |
| Aluminium | P80–P120 | P180–P240 | P320–P400 | P600 → P1500 wet, then polish | Wet from P400 | Aluminium clogs paper: use stearated or open-coat paper and a little water or WD-40 type lubricant. |
| Stainless steel | P60–P80 | P120–P180 | P240–P320 | P400 → P1200 wet, then polish | Wet from P400 | Use abrasives not previously used on carbon steel, or the stainless can rust-stain. |
| Brass, copper | P120 | P240 | P400 | P600 → P1500 wet, then polish | Wet from P400 | Soft: progress quickly through the grits to avoid dishing. |
| PLA / PETG prints | P120 (layer lines) | P220 | P400 (wet) | P600 → P1000+ wet | Wet from P220 | Dry sanding heats and smears PLA; sand wet, lightly. Filler primer fills layer lines faster than sanding alone. |
| ABS / ASA prints | P120 | P220 | P400 (wet) | P600 → P1000+ wet | Wet | Can also be vapour-smoothed with acetone (ventilate, no flames). |
| Resin (SLA/MSLA) prints | P240 (support marks) | P400 | P600–P800 | P1000 → P2000 for clear parts | Always wet | Wear nitrile gloves and a mask: sand only fully cured parts, wet, to keep resin dust out of the air. |
| Cured epoxy (river tables, coasters) | P80–P120 | P180–P240 | P400 wet | P600 → P3000 wet, then polish | Wet from P400 | Let epoxy cure fully first or it gums up the paper. A final flood coat is often quicker than polishing. |
| Acrylic edges | P240 | P400 | P600–P800 wet | P1000 → P2000 wet, then plastic polish | Wet | Keep the edge flat on a block. A flame-polish or CO2 laser cut avoids sanding. |
| Primer and paint (car, models) | P180–P240 (filler primer) | P320–P400 | P600 wet (before colour) | P1500 → P2500 wet, then compound | Wet | Flatten clear coat only once it is fully cured. Do not sand through edges and ridges. |
| Between coats of varnish, lacquer, oil | – | – | – | P320–P400 (or fine abrasive pad) | Dry | Just knock off dust nibs and give a key. Remove dust with a tack cloth. |
Polishing Compounds
Compound colours are a common convention, not a standard: one maker’s white may cut harder than another’s. Read the label for what it is meant to polish.
| Compound | Action | Use on | When |
|---|---|---|---|
| Brown / tripoli bar | Cutting | Aluminium, brass, copper, soft metals | Removes fine scratches after P600–P1200. |
| White bar | Medium cut to polish | Stainless steel, steel, hard metals | Follows a cutting compound on hard metals. |
| Green bar (chromium oxide) | Final polish | Stainless, chrome, hard metals; also sharpening strops | High-shine finishing compound. |
| Red / jeweller’s rouge | Final polish | Gold, silver, brass | Very fine; little cutting action. |
| Blue / plastic bar | Polish | Acrylic, plastics, resin, epoxy | Low-heat polish for plastics. |
| Liquid cutting compound | Cutting | Paint, clear coat, epoxy | After wet sanding with P1500–P3000, by machine or hand. |
| Liquid finishing polish | Final polish | Paint, clear coat, epoxy, acrylic | Removes haze left by cutting compound. |
Abrasive types
| Abrasive | Best for | Notes |
|---|---|---|
| Aluminium oxide | Wood, metal, paint | Tough, general purpose; the usual sanding disc and sheet. |
| Silicon carbide (wet and dry) | Paint, plastics, resin, metal finishing | Sharp and brittle; the black waterproof paper used for wet sanding. |
| Ceramic | Heavy removal on metal and hardwood | Long-lasting, best at higher pressure (belts, flap discs). |
| Zirconia | Steel and stainless grinding | Self-sharpening; common on flap discs. |
| Garnet | Hand sanding wood | Natural and soft; wears quickly but leaves a fine finish. |
How to Use This Chart
- Start only as coarse as you need. Every grit has to remove the scratches of the one before. Starting at P80 on a surface that only needs P150 adds two extra steps.
- Do not skip more than one grit. P80 → P120 → P180 is fine; P80 → P220 leaves deep scratches that show up under finish.
- Check scratches before moving on. Pencil squiggles on wood, or a guide coat of dry powder or spray on paint and filler, show where the previous grit’s scratches remain.
- Sand wet for plastics, resin, epoxy and paint from about P400. Water (with a drop of washing-up liquid) keeps the paper from clogging, stops heat build-up, and keeps dust out of the air. Use waterproof silicon carbide paper.
- Read the back of the sheet. A “P” before the number means FEPA. A number with no P on US paper is usually CAMI.
Worked example: polishing a cured epoxy river table to a gloss. Flatten with P80–P120 on a random orbital sander, then P180 and P240 dry. Switch to wet sanding at P400 and work through P600, P800, P1000, P1500, P2000 and P3000 pads. Finish with a liquid cutting compound and then a finishing polish. Use the Epoxy Resin Calculator to size the pour in the first place.
Dust: sanding dust from hardwood, MDF, epoxy, resin and old paint is harmful. Old paint may contain lead. Use extraction on power sanders, sand resin and epoxy wet, and wear an FFP3 mask for dry sanding.
Frequently Asked Questions
P grit is the European FEPA scale, used on most UK sandpaper. US sandpaper often uses the CAMI scale with no P. The two are nearly the same up to about 220 grit; finer than that, a P number is finer than the same CAMI number. For example, P400 is roughly CAMI 320.
Usually P150–P180 for most hardwoods and P120–P150 for softwoods and open-grained woods such as oak. Going much finer can burnish the surface so stain soaks in unevenly.
Start around P120 to remove layer lines, then P220 and P400. Sand wet from P220 to stop PLA heating up and smearing. For a paint finish, a filler primer and P400 wet sanding is quicker than sanding the bare plastic smooth.
Work up through the grits wet to P2000 or P3000, then use a cutting compound and a finishing polish. Many makers instead sand to about P400 and apply a final thin flood coat of epoxy for a full gloss.
It has a waterproof backing and a silicon carbide abrasive, so it can be used with water. Wet sanding keeps the paper from clogging, cools the work and traps dust. It is used on paint, plastics, resin, epoxy and for metal polishing.
Related Calculators and Charts
P-grade particle sizes follow the FEPA P scale (ISO 6344) and CAMI sizes the ANSI B74.12 scale, as reproduced in commonly published conversion tables; values are approximate averages. Grit sequences are typical workshop practice and starting points; finishes and materials vary, so test on an offcut.