How to Choose the Right Sandpaper Grit for Every Finishing Project

Sanding is the step that decides how a finish looks, yet the number printed on the back of the paper trips up more beginners than any other part of a project. Jump from a coarse grit straight to a fine one and every deep scratch reappears the moment stain hits the wood. This guide explains what those numbers mean, which grit belongs at each stage, and how to move through them without leaving marks behind.

What the grit number actually measures

The number on sandpaper refers to how many abrasive particles are packed into a given area of the backing. A low number means fewer, larger particles that cut aggressively; a high number means many small particles that polish. In the common CAMI grading scale used across North American hardware stores, 40 to 60 grit is coarse, 80 to 120 is medium, 150 to 180 is fine, and 220 and above is very fine.

Coarse grits remove material fast and leave visible furrows. Fine grits remove almost nothing and exist mainly to erase the scratches left by the grit before them. Understanding that relationship is the whole game: each grit's job is to remove the previous grit's marks, not to make raw wood magically smooth in one pass.

A grit progression you can rely on

The rule is simple. Start coarse enough to fix the worst flaw on the surface, then step up through the grits without skipping more than about 50 points at a time. Going 80 to 120 to 180 to 220 works; going 80 straight to 220 does not, because 220 is too fine to cut through 80-grit scratches. On flat surfaces a random-orbit sander keeps things even and cuts sanding time roughly in half compared with a hand block.

Here is where each grit range earns its place:

One caution about staining: sanding past 180 to 220 can burnish the wood and close the pores, so stain absorbs less and can look blotchy. For most stained pieces, stop at 180. Save 320 and finer for surfaces getting a clear film finish or for knocking down dust nibs between coats of polyurethane. If you are milling your own stock from rough pallet wood, expect to start as coarse as 60.

Matching the abrasive to the material

Grit number is only half the choice; the mineral doing the cutting matters too. Aluminum oxide is the default for wood, painted surfaces, and general DIY work. It is tough, long-lasting, and cheap, which is why it fills most variety packs. Silicon carbide is sharper and harder, cuts faster, and holds up to water, so it is the paper to reach for when wet-sanding between finish coats or working plastics and metal. Garnet is a softer natural abrasive that breaks down as you use it, exposing fresh edges and leaving a particularly clean surface on bare hardwood, though it wears out faster than aluminum oxide.

For a first kit, a pack of aluminum oxide in 80, 120, 180, and 220 grit covers almost everything a home woodworking setup will face. Buy decent paper rather than the cheapest roll; better backing and sharper grit last several times longer and clog less. Consult a broader guide to wood finishing when you move on to the film-finish stage.

Hand sanding versus power sanding

Both have a place, and most projects use them together. A random-orbit sander is the workhorse for large flat panels: it removes material quickly, spreads its swirl pattern randomly so marks are less directional, and saves your arms on a tabletop or a run of shelving. Its weakness is control at edges and detail, where it can round over crisp corners or dig if you tip it. Hand sanding with a firm block gives that control back. Wrap a quarter sheet around a cork or hardwood block for flat areas, and use a folded piece or a contour pad for moldings and corners. The one rule that overrides the tool choice is direction: whenever you finish by hand, sand with the grain, because cross-grain strokes leave lines that a stain darkens and highlights. A practical split is to power-sand the broad surfaces up through 150, then hand-sand the final grit and all the detail work with the grain.

The mistakes that leave scratches

Most sanding failures come down to five habits. Skipping grits leaves deep marks that finer paper cannot reach. Not vacuuming and wiping with a tack cloth between grits grinds loose coarse particles into the surface, cutting new scratches under your fine paper. Pressing too hard with an orbital sander digs swirls and low spots; let the tool's weight do the work and keep it moving. Hand-sanding across the grain instead of with it leaves lines that a stain will highlight instantly.

The fifth mistake is trusting worn paper. Once the grit dulls or clogs, it stops cutting and just generates heat, so you sand longer for a worse result. Paper is cheap; replace it often. A useful inspection trick between every grit is a raking light: shine a work lamp across the surface at a low angle, almost parallel to it, and remaining scratches, dents, and swirl marks jump out as shadows you would never see under overhead lighting. Check with that light before you move up a grit and again before the first coat of finish goes on a table top or any piece you want to look flawless.