Sandpaper Grit Progression Reference

A conventional grit progression for hand or power sanding wood, from coarse stock removal to fine pre-finish smoothing. Skipping too many grits in one jump makes it harder to remove the previous grit's scratch pattern.

Why the sequence goes up in these steps

Sanding does not smooth wood so much as replace one scratch pattern with a shallower one. Each grit has to cut away the valleys the last one left, so the step between them is kept small:

next grit ≤ roughly 2 × current grit
80 -> 120 -> 180 -> 220   works
80 -> 320                 does not

Jump too far and the fine paper spends its life polishing the tops of the coarse scratches instead of removing them. That takes longer than the skipped grit would have, and the marks appear anyway once finish darkens them. Start at the coarsest grit the surface needs - 80 for mill marks, 40-60 only for rough-sawn stock or old finish.

Where to stop, and how

Stain or dye: stop at 150-180. Finer paper burnishes the surface and closes the pores, so the colour lands lighter and blotchier.
Clear film finishes: 180-220 is plenty; the film, not the wood, carries the gloss.
320 and up: for scuffing between coats, not for bare wood.
Between grits: vacuum and wipe. One stray 80 grit particle dragged under a 220 pad leaves a scratch you will only see under finish.

Sand along the grain, and hand-sand the final grit even after a random-orbit sander - orbital swirls run across the fibres and show under stain.

These are CAMI numbers, the US convention. European P-grades match closely to about 220, then diverge: P400 is around 35 microns against CAMI 400's 22, so P400 is the coarser paper despite the same figure.

Frequently asked questions

What grit should I sand to before staining?

180 on hardwood, 150 on softwood. Anything finer polishes the surface closed and the stain sits on top rather than soaking in, which is a common cause of patchy colour.

Can I skip from 80 grit straight to 220?

You can, but it costs time rather than saving it. Work 120 and 180 in between; each takes a few minutes, while 220 alone can take half an hour to clear 80 grit scratches.

Do I need to sand between coats of finish?

Yes for most film finishes. A light pass with 320 knocks down raised grain and dust nibs and gives the next coat something to key to. Sand only enough to dull the sheen.