What Size Sanding Belt Do You Need? 

Need to replace a sanding belt but don’t know the size? Whether your old belt is worn out, missing, or you just forgot the specs, there are several easy ways to figure it out. Below are 8 simple methods to help you measure a sanding belt—whether you still have it or not.

Ways to Measure a Sanding Belt

If You Have a Belt Available

METHOD 1: Check Your Belt’s Inside (Most Accurate)

This may seem pretty obvious to a lot of people, but your old belt should have the size printed on the inside of the belt. Some companies may not add them or it may have worn off from use. If that’s the case, there are 7 more methods to try below.

METHOD 2: Cut and Measure (2nd Most Accurate)

If you’re okay sacrificing one of your sanding belt, grab some scissors or a blade and make a cut straight across. Lay it out on a flat surface and measure the full length. Then measure the width. That’s it…you’ve got the exact dimensions.

Example: If your belt measures 48” long when cut and 2” wide, you need a 2” x 48” sanding belt.

? Pro Tip: Use a soft tape measure or lay a ruler end-to-end for more precise results

METHOD 3: Wrap with String

Too soon to sacrifice one of your sanding belts? No problem. Wrap a string or soft measuring tape around the belt. If using string, mark it where the end meets the rest of the string, then lay out the string, measuring it from the end to the marked spot. If you’re using soft measuring tape, just take the measurement where it meets and use that for your length. 

METHOD 4: Press Flat & Measure

Flatten the belt on a hard surface. Measure the length of the belt and double that number. That will get you the length.

Example: If your flattened belt measures 18” from fold to fold, you’ll multiple that by 2 to get 36”. Then if its 4” wide, you need a 4” x 36” sanding belt

METHOD 5: Roll It Out

Place the belt upright on its edge and roll it in a straight line on a flat surface (like a table or floor), marking the start and end point after one full rotation. Then measure the distance between the two points — that’s your length. Measure the width normally.

This is a little trickier to get perfect, but handy if you don’t want to cut the belt and don’t have string nearby.

If You Don’t Have a Belt Available

METHOD 6: Check Product Manual (Tied for Most Accurate)

If you still have the manual for your sander—or can find it online—there’s a good chance it lists the compatible belt size. Most manuals include this in the specifications section or under replacement parts.

If you can’t find the paper manual, try searching for your sander’s make and model followed by “manual” or “specs” online. Example search: “Makita 9403 manual sanding belt size” - Google's AI results give the answer, but you can still look for the manual to double-check.

METHOD 7: Measure your Belt Sander Tool

If you don’t have a belt and can’t find the size listed anywhere, you can still get a pretty accurate measurement using a piece of string and your actual sander.

Take a string, strip of paper, or flexible measuring tape and wrap it around the sander exactly where the belt would go—following the same path over both rollers. Pull it snug (but not tight enough to stretch), then mark or cut the string where it meets the starting point. Lay it flat and measure the total length.

That gives you the belt length.

Then measure the width of the roller to figure out the belt width.

METHOD 8: Look at Past Orders

If you’ve bought sanding belts online before, check your order history, emails, or even the packaging (if you kept it). Retailers like Empire Abrasives, Amazon, and others usually keep detailed order info that includes belt size.

Why Belt Size Matters

Using the wrong size sanding belt might not seem like a big deal…until it is. A belt that’s too long won’t stay tight and can slip during use, while one that’s too short either won’t fit at all or could strain your sander’s motor. Even a small mismatch can lead to poor tracking, uneven sanding, or damage to your machine.

If you’re unsure of the size, it’s always worth double-checking before you buy. And if you’re ready to grab a replacement, you can check out our full selection of sanding belts in every popular size and material.

Getting the right fit means smoother work, safer sanding, and longer tool life.

Pro Tips to Make It Easier Next Time

Once you figure out your belt size, save yourself the trouble next time by doing one (or more) of the following:

• Write the size on your sander - Use a permanent marker or a small label and stick it somewhere on the tool. It’s a quick way to make sure you or anyone else using the sander knows exactly what size to buy later.
• Save the packaging from your next belt - Most belts come in a bag or box with the size printed on it. Toss it in your toolbox or drawer for quick reference next time.
• Take a photo of the belt label - Snap a picture of the size printed on the inside of the belt before it wears off. 
• Add it to your notes app or workshop whiteboard - A little digital or analog recordkeeping can go a long way if you have multiple tools or work in a shared space.

FAQ

Can I measure a sanding belt without cutting it?

Yes! You don’t have to cut your belt to measure it. Try wrapping a string around the inside of the belt, marking where it meets, and then measuring the string’s length. This gives you a close estimate of the belt’s total length while keeping the belt intact.

What happens if I get the wrong size sanding belt?

A belt that’s too long may slip or won’t track properly, while a belt that’s too short won’t fit at all—or could stress your machine. Even a small size mismatch can cause uneven sanding, poor performance, or damage to the sander itself.

Where can I find custom sanding belts?

Right here. Empire Abrasives offers custom sanding belts made to order in a wide range of sizes, materials, and grits. Just get in touch with our sales team with your specs and we’ll take care of the rest.

Can I reuse sanding belts?

In some cases, yes. If the belt isn’t clogged or worn out, you can reuse it. Just make sure it still tracks properly and hasn’t lost its grit. For longer life, use a belt cleaning stick to remove debris.