Table of Content
- What is sandpaper Abrasive grit and how is it measured?
- The CAMI vs. FEPA Scale: Primary grading scales to measure coarseness
- The Sandpaper Grit Chart: A Practical Reference
- How to Choose the Right Sanding Grit for Your Project
- Types of Sandpaper Materials
- Open-Coat vs. Closed-Coat Sandpaper
- Hand Sanding vs. Power Sanding: Matching Your Tool to the Grit
- Common Mistakes to Avoid
- Conclusion
Walk into any hardware store and you'll find an entire wall of sandpaper, dozens of options in different colors, materials and numbers. For first-timers, it might be overwhelming. Even for experienced craftsmen, grabbing wrong grit can mean hours of extra work, a ruined surface, or an unsatisfactory finish.
This sandpaper grit guide is an attempt to clear the confusion. Whether you're stripping old paint off a deck, sharpening a blade, smoothing a piece of hardwood, or treating bare metal for a topcoat, the right abrasive grit size makes all the difference. Here's everything you need to know.
What Is Sandpaper Abrasive Grit and How Is It Measured?
This is level one of this sandpaper grit guide. Grit refers to the size of the abrasive particles bonded to the sandpaper's surface. The measurement works like a shield: sandpaper manufacturers filter abrasive particles through a screen with a set number of openings per square inch. If 60 particles fit through the screen at once, the result is 60-grit sandpaper. If 220 particles fit through, you have 220-grit.
The logic of this sandpaper grit guide flows naturally from there. Fewer particles per inch means each particle is larger, and larger particles cut more aggressively. More particles per inch means finer particles that leave a smoother surface. This is why coarse sandpaper has a low number and fine sandpaper has a high one.
The CAMI vs. FEPA Scale: Primary Grading Scales to Measure Coarseness
Not all sandpapers are labeled the same way. There are two widely used grading systems and understanding each of them saves a lot of efforts.
CAMI (Coated Abrasives Manufacturers Institute) is a system you'll encounter at most US hardware stores and lumber yards, with grit numbers like 40, 80, 120, and 220 (no prefix, no letters). It is a popular grading standard in North America however, FEPA is a more widely used in the US market currently.
FEPA (Federation of European Producers of Abrasives) is the international standard, used across North American Markets, Europe, and widely adopted in global manufacturing. FEPA grits are identified by a "P" before the number: P40, P80, P120, P220. The FEPA system is also recognized for its strictness when it comes to particle size, meaning manufacturers must meet tighter standards to earn each grit rating.
For coarser grits, anything below around 180, the two systems are close enough to use interchangeably. But at finer levels the gap widens meaningfully. CAMI 400 is almost equivalent to FEPA P800. If you're wet-sanding for a smooth finish and you accidentally grab FEPA paper assuming it is equivalent to CAMI, you could end up working with a significantly finer abrasive than expected. Always check the packaging for the "P" prefix.
The Sandpaper Grit Chart: A Practical Reference
Below is a sandpaper grit chart to leverage your project planning:
| Category | FEPA Grit | CAMI Grit | Typical Uses |
|---|---|---|---|
| Extra Coarse | P8 – P36 | 8 – 36 | Removing thick paint or varnish |
| Coarse | P40 – P80 | 40 – 80 | Rough shaping, removing old finishes, leveling uneven surfaces |
| Medium | P100 – P220 | 100 – 220 | General smoothing, surface prep, removing planer marks |
| Fine | P240 – P320 | 240 – 320 | Pre-finish sanding, refining light surfaces |
| Very Fine | P400 – P600 | 360 – 600 | Between-coat sanding, metal polishing, light finishing |
| Ultra Fine | P800 and above | 800 and above | Wet sanding, high-gloss finishing, blade sharpening |
SurfPrep offers best quality sandpapers and sanding products with a full range of grit sizes. Visit SurfPrep and shop by Abrasive size.
How to Choose the Right Sanding Grit for Your Project
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The grit number tells you how fine or coarse the sandpaper is. The material tells you how aggressively it cuts, how long it lasts, and what surfaces it's suited for. These are the four most common types.
Aluminum Oxide
Aluminum oxide is one of the most widely used abrasive materials in woodworking and general metalworking. It's cost-effective, widely available, and works across a broad range of materials including wood, metal, and plastic.
Silicon Carbide
Silicon carbide is sharper and harder than aluminum oxide, making it well-suited for harder materials like glass, stone, ceramics, and non-ferrous metals. It is also the preferred choice for wet sanding because it resists water and generates less heat during use.
SurfPrep offers a range of silicon carbide options for every application:
- For sheets, check out the SurfPrep 9" x 11" Wet Dry Silicon Carbide Sheet : ideal for varnish, paint, stain, and other finishes.
- For disc sanding, the 5" Lux Abrasive Discs and 6" Lux Abrasive Discs deliver consistent silicon carbide performance with Hook & Loop convenience : 25 discs per box.
- Prefer a net-style disc? The 5" SurfNet Discs and 6" SurfNet Discs are worth a look.
- For heavy rust removal on metal, the SurfPrep Non-Woven Hand Pads are the most aggressive non-woven option in the lineup: resists loading and works wet or dry.
Ceramic
Ceramic abrasives sit at the top of the ladder when it comes to durability. They stay sharp over extended use, making them cost-effective for industrial and high-demand applications despite a higher upfront investment. Most manufacturers offer ceramic sandpaper from 24 to 120 grit, though some specialty producers offer ceramic belts up to 400 grit. Ceramic is ideal for tough surfaces where other abrasives would wear down quickly.
Check these out:
- 6" SurfPrep Ceramic White Lightning Paper Abrasive Discs
- 5" SurfPrep Ceramic White Lightning Paper Abrasive Discs
Open-Coat vs. Closed-Coat Sandpaper
This distinction rarely gets the attention it deserves, but it directly affects how long your sandpaper lasts and how well it performs on specific materials.
Closed-coat sandpaper has abrasive grains covering nearly the entire surface of the backing (close to 100%). This high density makes it aggressive and consistent, ideal for hard, dense materials like metal where the surface doesn't generate a lot of soft debris that clogs the paper.
Open-coat sandpaper covers only 50% to 70% of the backing surface with abrasive grains. The gaps between particles give debris somewhere to go, like sawdust, resin, and soft material fibers accumulate in the spaces rather than loading up between grains. This makes open-coat the better choice for softwoods, resins, and painted surfaces where clogging can be a major problem.
Semi-open (or semi-closed) sandpaper falls between the two, with roughly a 30% reduction in grain coverage compared to a fully closed coat. It balances the efficiency of open-coat with some of the aggressive cutting of closed-coat, making it a versatile middle option for mixed-material work.
A quick thumb rule: if your sandpaper clogs within a few minutes of use, you need a more open coat (coated with zinc stearate) designed specifically to resist loading.
Hand Sanding vs. Power Sanding: Matching Your Tool to the Grit
The tool you're using changes how a given grit behaves — and that directly affects which grit you should reach for.
Hand Sanding
Hand sanding gives you the most control and is the gentlest option of the lot. Lower speed and pressure mean shallower scratches, making it ideal for final passes, curved surfaces, and detailed areas. Always sand with the grain — cross-grain scratches are stubborn and hard to fix later.
Shop now for an unbelievable hand sanding experience→
- SurfPrep’s Hand Sanding Block
- SurfPrep’s RAD Pads Pro
- SurfPrep’s SurFlex Foam Roll Hand Pads
- SurfPrep Non-Woven Hand Pads
- 1” Single Angle Block Brown (A/O)
For more options, explore SurfPrep's full hand sanding collection.
(Pay over time for orders above $35)
Random Orbital Sanders
Random orbital sanders are the most popular power sanding tool for a reason. Their random, circular motion reduces visible scratch lines, making them far more forgiving than belt sanders. They work well from 60 grit through 220 grit and handle most surface prep jobs comfortably.
Shop now →
SurfPrep’s random orbital sander variants:
- 5" Trident Air Sanders
- 5" Electric Ray Gen 2+ Sanders
- 6" Trident Air Sanders
- 6" Electric Ray Gen 2+Pro Sanding System Kits
Visit to explore the full range:
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(Pay over time for orders above $35)
Belt Sanders
Belt sanders are fast, powerful, and built for heavy lifting — leveling large surfaces and knocking down thick material quickly. They're unforgiving though; a second too long in one spot and you've got a dip that's hard to fix. Use them early, then hand off to a random orbital or hand sanding to refine.
Shop now → SurfPrep’s Portable Sanding Belts
(Pay over time for orders above $35)
Common Mistakes to Avoid
You may find sandpaper grit guide circling around the internet, but very few of them talks about the common mistakes to avoid. Recognize these mistakes to save time and efforts.
- Skipping grit levels. Jumping from P60 straight to P220 seems like a time saver but creates the opposite effect. Fine grits can't efficiently remove the deep scratches left by coarse grits. Move up one or two grit levels at a time.
- Using the wrong sandpaper type for the material. Open-coat aluminum oxide clogs quickly and wears out fast. Silicon carbide for fine metal finishing doesn't make sense on rough wood stock. Matching the abrasive material to the job is as important as choosing the right grit number.
- Over-sanding. More sanding is not always better. Over-sanding can thin out material and alter the shape of edges. Sand to the right point and stop.
- Not cleaning the surface between grits. Coarse dust and abrasive particles left on the surface from a previous grit get picked up by the finer paper and drag across the surface. This creates the exact scratches you're trying to eliminate.
- Sanding against the grain on wood. This creates more visible grain scratches as they disrupt the natural pattern of wood. Always decide a proper direction before sanding.
Understand the game.
Conclusion
Every project has a starting point and an end goal. The sanding process connects both. This sandpaper grit guide will help you navigate the ways to achieve a perfect finish.
Start by reading your material. Is it soft and prone to clogging the paper? Go open-coat. Is it hard metal that needs aggressive removal? Look at ceramic or zirconia. Are you finishing clear coat on a car panel? You'll be wet-sanding with silicon carbide and progressing through abrasive grit sizes.
Plan your sanding carefully and start with the right grit today!
Shop now at https://surfprepsanding.com/