Quick answer: A sanding belt is sized as width × length, where length is the full circumference. Measure the width across the belt. For the length, either lay the belt flat, measure end to end and double it, or cut the belt at the joint and measure it flat. A belt that measures 4" across and 18" laid flat is a 4" × 36" belt.
Why the exact size matters
Sanding belts come in hundreds of widths and lengths, and a belt that's a half inch long won't track and a half inch short won't go on. Getting the precise measurement is essential when it's time to reorder, especially for lapidary belts, European and Asian machines, and older sanders that use sizes no distributor stocks.
Two ways to measure a sanding belt
1. Measure a whole belt and double it
Measure the width first. Then lay the belt as flat as you can without creasing it, measure from one end to the other, and double that number – it's a loop, not a sheet. This is quick and works fine for common sizes.
2. Cut the belt and measure it flat (most accurate)
Measure the width, then cut the belt straight across – directly down the middle or along the tape joint. Lay it out flat and measure from one end to the other. That number is your belt length. This is the best method for an old belt you're done with, and the only reliable one for odd sizes: some belts are 25-7/32" long, and method one tends to round that up or down, which causes tracking problems on the machine.
Don't have a belt to measure?
Release the tensioner, wrap a tape or a piece of string around both rollers along the path the belt takes, and measure that. Check the sander's manual too – most list the belt size – and look for a size printed on the inside of any old belt.
Where to order a custom size sanding belt
Maverick Abrasives manufactures custom sanding belts every day for conventional and unconventional machines, in any width and length, in aluminum oxide, zirconia, ceramic or silicon carbide, in about three business days. Order a custom belt online, email sales@maverickabrasives.com, or call 714-646-3299.
