How to Choose the Right Sandpaper Grit for Your Project

Choosing the right sandpaper for your project starts with understanding grit numbers. Each number represents the sandpaper's coarseness, with lower numbers being coarser and higher numbers being finer. Coarser sandpaper sands material more aggressively than finer sandpaper. Read ahead to learn how to choose the right sandpaper grit for your project.

What Is Sandpaper Grit?

Sandpaper grit is a number that determines the coarseness of sandpaper. In other words, this number determines how aggressively the sandpaper will sand a given material. Contrary to popular belief, the number itself doesn't refer to the number of abrasive particles on the paper, but rather the number of holes per inch on the screens used to sift the particles in the manufacturing process.

The more holes per inch in the screen, the smaller the holes. This results in smaller abrasive particles distributed on the paper. The fewer holes per inch, the larger the holes, which results in larger abrasive particles on the paper.

Sandpaper Grit Vs. Sandpaper Grade

So what is the difference between sandpaper grit and sandpaper grade? Sandpaper grit is a number rating based on the manufacturing process, such as 80, 120, and 220, while sandpaper grade is a general class of sandpaper coarseness, including coarse, fine, very fine, and extra fine. Each sandpaper grade consists of a range of grits.

How Sandpaper Works

Regardless of whether you're hand-sanding, using a power sander, or using coarse sandpaper versus fine sandpaper, all sandpaper works in the same way. The grit consists of abrasive particles that are attached to a backer, often made from paper or cloth. As the sandpaper moves on the material's surface, each abrasive particle makes a cut. The sandpaper's grit number will determine how many cuts there are and how deep each cut is. Finer sandpaper grits make cuts that are hardly visible to the naked eye, while coarser grits leave deep gouges that can be unsightly.

Because of this, the sanding process usually involves starting with lower grits and advancing to higher grits. Each increasing grit number will smooth the scratches left by the former grit, resulting in a surface that's smooth to the touch and without visible scratches.

How to Choose the Right Sandpaper Grit

Choosing the right sandpaper grit depends on your project, material, and what you need the sandpaper to accomplish. More than likely, you'll need to use several incremental grits.

For example, if you're refinishing a piece of wood furniture, you'll start with a coarse grit like 80 to remove the finish and smooth any imperfections. Next, you'll advance to a finer grit like 100 or 120 to smooth the scratches left behind by the 80-grit sandpaper. From there, your next grit will be determined by your finish. If you plan to paint the piece or apply a film finish such as polyurethane, it's likely ready to go. If you plan to apply a penetrating finish like a stain or penetrating oil, continue advancing grits to 150 to 220.

Consider the Wood Finish

The reason for this is the nature of the finishes themselves. Finishes that sit on the wood's surface (paint, polyurethane, lacquer, etc.) hide the fine scratches left by 120-grit sandpaper. However, penetrating finishes (stain, Danish oil, penetrating oil, etc.) soak into the scratches, highlighting their visibility.

Starting with too high of grit will result in wasted time and effort. Plus, you'll burn through sandpaper quickly trying to remove finishes or smooth rough material with higher-grit sandpaper. However, starting with too low of grit can result in damage to your project that is hard or impossible to undo. For example, you can quickly ruin wood details on furniture by eating through them with coarse sandpaper. Finding the right sandpaper to start with is about finding a balance between too coarse and too fine.

Sandpaper Grit Chart

Reference the table below to choose your start and end grit, then advance through the grits between them for the best results and most efficient sanding.

Sandpaper Grits and Their Purposes
Sandpaper Grit	Grade	Purpose
Less than 40	Extra-Coarse	Refinishing floors and stripping old finishes
40 to 60	Coarse	Smoothing rough material and shaping wood
80	Medium	Stripping paint, blending joint seams, and rounding sharp edges and corners
100 to 120	Fine	General sanding, surface prep for painting and film finishes
150 to 220	Very-Fine	Scuffing glossy surfaces, removing rust from metal, surface prep for penetrating oils
320 to 360	Extra-Fine	Sanding between finish coats, cleaning metal surfaces
400 to 600	Super-Fine	Polishing wood and metal, sanding between finish coats, wet sanding (when waterproof)
800 and up	Ultra-Fine	Polishing wood and metal, sanding after final finish coats, wet sanding (when waterproof)

Which Sandpaper to Buy for Your Sander

More important than sandpaper grit is its compatibility with your sander. If you buy the appropriate grit for the job in a round disc but you have a belt sander, you won't get anywhere. Here are some common sanders, each with its own specific type of sandpaper:

• Orbital Sander
• Belt Sander
• Drum Sander
• Palm Sander
• 1/4-Sheet Sander
• Drywall Sander

Beyond each type of sander calling for different sandpaper, many of them come in different sizes that use smaller or larger sandpaper. Pay close attention to the type of sander you have, its size, and the sandpaper you're buying to ensure it's compatible.