Sandpaper Grit Guide: What Do P40, P80, P120, P180, P240 & P320 Mean?

Choosing the right sanding grit can make surface preparation much quicker and help avoid doing unnecessary work. The basic rule is simple: lower grit numbers are coarser and remove material more aggressively; higher grit numbers are finer and produce a more refined scratch pattern.

Shop the products in this guide ↓

But knowing that P40 is coarse and P320 is fine is only the start. The useful question is where each grit fits in a sanding sequence and when you should move to the next one.

Sanding grit guide at a glance

These are practical starting points rather than universal rules. The correct grit depends on the material, existing finish, coating system, tool, pressure and final result you need. Always follow the recommendations of the coating, paint, filler or material manufacturer when they specify a sanding sequence.

What does the P in P40 or P320 mean?

The grit number describes the abrasive's grading. In everyday use, the important point is the progression: a coarse abrasive such as P40 creates a deeper scratch pattern and removes material quickly, while a finer abrasive such as P320 removes less material and leaves a finer scratch pattern.

That is why sanding is usually done in stages rather than trying to go from a very rough surface straight to a very fine abrasive.

What is P40 grit used for?

P40 is at the aggressive end of the range. It is useful when substantial material needs to be removed at the start of a job. Because it cuts quickly, it also leaves a comparatively coarse scratch pattern, so it normally needs to be followed by finer grits if the surface is going on to a more refined finish.

Use coarse abrasives with control. Removing material quickly is useful only when you are not removing more than the job requires.

What is P60 grit used for?

P60 is still a coarse abrasive, but it gives you another step between very aggressive initial sanding and more general preparation. It can be useful for continuing stock removal while beginning to reduce the deeper marks produced by a coarser first stage.

What is P80 grit used for?

P80 is commonly used as a coarse preparation grit. It remains capable of meaningful material removal but is less aggressive than P40 or P60. It is a useful stage when refining a surface after heavier work or when the job does not require the most aggressive starting grit.

What is P120 grit used for?

P120 sits in a useful intermediate position. It is suitable for general preparation and for refining the scratch pattern left by coarser abrasives before moving into finer sanding stages.

If a surface is already reasonably sound and does not need heavy material removal, you may not need to start as low as P40. Starting with the least aggressive grit that will do the job can help avoid unnecessary sanding.

What are P180 and P240 used for?

P180 and P240 move the job into finer preparation. They remove less material per pass and create a progressively finer scratch pattern. These grits can be useful after intermediate sanding when you need to refine the surface further before the next stage of the finishing process.

Whether P180 or P240 is suitable immediately before a coating depends on that coating system. Check the paint, primer, filler or finish manufacturer's preparation instructions rather than assuming one grit is correct for every product.

What is P320 grit used for?

P320 is a fine abrasive in this range. It is useful for later-stage preparation where the aim is refinement rather than heavy stock removal. At this stage, technique matters: excessive pressure or sanding for too long can still alter edges, profiles and surface shape.

Should you skip sanding grits?

You do not always need to use every grit in sequence, but making very large jumps can leave coarse scratches that the finer abrasive takes much longer to remove.

A sensible approach is to choose a starting grit based on the amount of material that actually needs removing, then move through progressively finer grits until you reach the surface condition required for the next operation.

For example, a job that genuinely needs heavy initial sanding might move from a coarse grit into an intermediate grit and then into finer preparation. A surface that already needs only light preparation may start much higher.

How do you know when to move to the next grit?

Do not judge only by how long you have been sanding. Inspect the surface. The aim of each stage is to create a reasonably consistent scratch pattern and remove the defects or deeper scratches that the current grit is intended to address.

Once the surface is consistent for that stage, moving to the next grit is usually more efficient than continuing to sand with the same abrasive.

Random orbital sanding and dust extraction

For machine sanding, the abrasive must match the sander and backing pad in size, attachment type and hole pattern. Dust-extraction holes only help when they line up with a compatible backing pad and extraction system.

The SIA Abrasives 1944 siaone 150mm 15-Hole Sanding Discs stocked by Kenrika are hook-and-loop discs for compatible 150mm / 6-inch random orbital sanders. The range is available in P40, P60, P80, P120, P180, P240 and P320, making it possible to move from coarse preparation through progressively finer sanding using one disc format.

Do not forget abrasive condition

A worn or clogged abrasive does not cut in the same way as a fresh one. If a disc has stopped cutting effectively, is damaged or has become heavily loaded with material, replacing it can produce a more consistent result than increasing pressure.

Excessive pressure can also reduce control and may interfere with effective machine sanding. Let the abrasive and suitable tool do the work.

Safety when sanding

Sanding can create airborne dust and debris. Use appropriate eye protection and consider suitable respiratory and hearing protection according to the material, tool and task. Use dust extraction where appropriate and follow the safety guidance supplied by the abrasive, power-tool and material manufacturers.

You can browse our PPE & Safety range for related protective equipment.

Shop sanding and surface-preparation supplies

Browse the full Abrasives & Consumables collection for sanding discs, sanding blocks, cutting and grinding products and other preparation supplies.

If you need larger quantities or help sourcing a particular abrasive or grit, use our Trade & Bulk Enquiries page.