How sandpaper grit numbers work

Sandpaper grit numbers tell you how aggressively the abrasive will cut. Lower numbers are coarser and remove material quickly; higher numbers are finer and leave a smoother finish. For most wood projects, start with the coarsest grit needed to remove the defect, then move through progressively finer grits until the surface is ready for paint, stain, or clear finish.

What sandpaper grit numbers mean

Grit refers to the size and spacing of abrasive particles on the sanding material. The number is not a hardness rating and does not directly indicate how durable the paper is.

A low number, such as 40 or 60, has relatively coarse abrasive particles. It cuts quickly but leaves deep scratches. A high number, such as 220 or 320, uses finer abrasive particles. It removes less material per pass and leaves a smoother surface.

A simple rule is:

• Lower grit number = faster stock removal and deeper scratches
• Higher grit number = slower cutting and a smoother surface

The number alone does not tell you everything. Abrasive type, backing material, paper quality, sanding pressure, and whether the product is designed for hand sanding or a power sander also affect performance.

Common sandpaper grit ranges

These ranges are general guidelines. The best starting point depends on the surface condition and the finish you want.

Very coarse grits: 24 to 60

Very coarse sandpaper is used for substantial material removal, such as:

• Removing thick coatings or heavy rust
• Leveling uneven wood or damaged surfaces
• Shaping wood quickly
• Removing deep defects

Use these grits carefully. They can create scratches that are difficult to remove, especially on softwood, veneer, thin materials, and finished surfaces.

Medium-coarse grits: 80 to 120

These are common general-purpose grits for wood preparation. They can help with:

• Smoothing rough boards
• Removing remaining marks from coarse sanding
• Preparing bare wood before finer sanding
• Removing old finish when the coating is not extremely thick

For many unfinished wood projects, 80 or 100 grit is a practical starting point when the surface needs noticeable correction.

Medium-fine grits: 150 to 180

These grits refine the scratches left by coarser abrasives. They are often useful for:

• Final preparation of bare wood before many finishes
• Smoothing previously sanded paint or filler
• Refining furniture surfaces
• Preparing between coats when a finish manufacturer allows sanding

Stopping at 150 or 180 may be appropriate for some painted projects. Sanding much finer than necessary can reduce the mechanical grip needed by certain coatings.

Fine grits: 220 to 320

Fine sandpaper is used when you need a smoother surface with relatively light material removal. Typical uses include:

• Smoothing wood before clear coating
• Sanding between coats of finish
• Removing minor surface roughness
• Refining a painted or sealed surface before another coat

A 220-grit product is a common choice for light finishing work, but always follow the coating manufacturer's instructions for between-coat sanding.

Extra-fine grits: 400 and higher

Extra-fine abrasives are used for delicate finishing, polishing, and smoothing certain coatings. They are not usually the right choice for correcting dents, leveling uneven wood, or removing substantial paint.

At this range, the specific abrasive, backing, lubricant, and surface finish matter more. Wet-or-dry products may be intended for use with water or another approved lubricant, while ordinary dry sandpaper may not be.

Which grit should you start with?

Choose the least aggressive grit that can accomplish the job. Starting too fine wastes time because the abrasive may not remove the defect efficiently. Starting too coarse can create unnecessary scratches.

Use these starting points as general guidance:

These ranges are not a substitute for the product instructions. A delicate veneer, softwood, water-based finish, or thin paint layer may require a gentler approach.

Why you should progress through grits

Each grit removes scratches made by the previous grit. Moving to a much finer grit too soon can leave deep scratches behind. Continuing with a coarse grit for too long can create more damage than necessary.

A common progression might be:

• 80 grit
• 120 grit
• 180 grit
• 220 grit

You do not always need every step. If the surface is already fairly smooth, you might begin at 120 and move to 180 or 220. If you start with 40 grit, adding intermediate steps such as 60, 80, and 120 may make it easier to remove the deeper scratches.

Before changing grits, inspect the surface under good lighting. The scratches from the previous grit should be relatively uniform, with no obvious deep marks, shiny patches, or leftover finish in areas you intended to sand.

Sandpaper grit systems: CAMI and FEPA

Products may use different grit-numbering standards. In the United States, you may commonly see the CAMI system. Many products made to European standards use FEPA, often marked with a P before the number, such as P120 or P240.

CAMI and FEPA numbers are not always directly interchangeable. A product marked P120 should not automatically be assumed to have exactly the same abrasive grading as a product marked 120 without the P designation.

For ordinary woodworking, the difference may not change your entire sanding plan, but it matters when you need consistent results or are matching replacement sheets and discs. Check the package or manufacturer's grit chart when switching systems.

Grit is different from abrasive material

Grit number describes particle size, but abrasive material affects how the product cuts and wears.

Common abrasive materials include:

• Aluminum oxide: A widely used general-purpose abrasive for wood and many coatings.
• Silicon carbide: Often used for fine finishing and wet-or-dry applications; it can cut sharply but may wear differently from aluminum oxide.
• Ceramic abrasive: Often designed for fast cutting and longer performance in demanding applications.
• Garnet: Used in some wood-sanding products and can produce a useful finish, though it may wear more quickly.

The best choice depends on the material, sanding method, and finish. A higher grit made from one abrasive is not necessarily identical in behavior to the same number made from another.

Sheet, disc, sponge, and block formats

Grit numbers work the same basic way across formats, but the backing and shape affect how the abrasive behaves.

Sandpaper sheets

Sheets are useful for hand sanding, sanding blocks, edges, corners, and irregular areas. They can often be folded or cut, but follow the product instructions and avoid creating folds that concentrate pressure on a finished surface.

Sanding discs

Discs are designed for compatible power sanders. Confirm the disc diameter, attachment style, hole pattern, and sander type before buying. A disc with the wrong configuration may not attach correctly or may not collect dust properly.

Sanding sponges

Sanding sponges conform more easily to profiles, rounded edges, and trim. They are convenient for light hand sanding, but they may not keep a perfectly flat surface as level as a rigid sanding block.

Sanding blocks

A rigid block helps distribute pressure evenly and reduces the chance of creating finger-shaped grooves. It is often a better choice than loose folded paper when sanding broad, flat areas by hand.

How to avoid common grit mistakes

Do not use pressure to compensate for the wrong grit

Pressing harder can increase cutting briefly, but it can also clog the abrasive, create uneven scratches, wear the paper quickly, and round over edges. Switch to a more suitable grit instead.

Do not skip inspection between grits

Dust can hide scratches and leftover finish. Vacuum or wipe the surface as appropriate, then inspect it before moving on.

Do not sand veneer or thin coatings aggressively

Veneer can be sanded through quickly. Start with a finer grit, use light pressure, and avoid lingering in one spot with a power sander.

Do not assume a finer grit is always better

Paint, primer, and some finishes need enough surface texture to bond. Sanding far beyond the coating manufacturer's recommendation may make the surface too smooth or remove more material than intended.

Match the product to the sander

Use the correct abrasive format and follow the sander's instructions. Keep dust collection connected when appropriate, and wear suitable eye and respiratory protection. Some sanding dust and old coatings can be hazardous; do not sand unknown or potentially lead-containing paint without following applicable safety guidance.

A practical grit-selection process

1. Identify the surface: bare wood, painted wood, filler, metal, plastic, or finish.
2. Decide what must be removed: roughness, scratches, paint, gloss, or only minor dust nibs.
3. Start with the least aggressive useful grit.
4. Sand evenly and inspect the surface.
5. Move to the next finer grit once the previous scratches are uniform.
6. Stop when the surface meets the requirements of the next finish or coating.

If the paper clogs almost immediately, the coating may be soft, uncured, or incompatible with dry sanding. Let the finish cure according to its instructions, clean the abrasive when appropriate, or use an abrasive product intended for that coating.

When to replace sandpaper

Replace or rotate the abrasive when it stops cutting, becomes clogged, tears, loses its backing, or produces inconsistent scratches. A worn sheet can make sanding slower and encourage excessive pressure.

If you repeatedly need to sand through several grit changes, a multi-grit assortment can be convenient. For a power sander, buy the correct disc or sheet format rather than trying to adapt an incompatible product.

The key idea is simple: use a coarse grit only when you need its cutting power, then refine the surface with progressively finer abrasives until it is ready for the next step.