We see it all the time.  A customer needs to replace their worn out V-belts but after a few years of running, all the numbers on it are worn off.  Or even worse, it’s been run to the point of looking like nothing but a loop of string with a little bit of rubber stuck on it.  So how the heck do you figure out what belt to replace it with?  Here’s how.




The first step is to determine which cross section the belt is.  This will ensure that it seats properly into the pulley sheave.  Using a pair of calipers to get an accurate reading, measure across the top, widest point of the belt.  Now refer to the chart below to select which cross section you have.  Note that some cross-sections are very close in size.  This is why it’s important to get an accurate measurement with calipers.  It is also possible that the belt has worn it’s edges beyond the point of being able to correctly measure it.  In this case, you will need a special gauge to measure the groove of the pulley and obtain the belt cross section (We have free ones we can give out!  Just email us or stop by our service counter.)




To get the length, mark a starting point on the outside or topside of the belt.  Using a flexible english measuring tape, measure all the way around the outside back to the starting point and take note of that measurement.



If you have determined that you have a 3V, 5V, or 8V simply take the length you measured, add the cross section in front if the length and add a 0 to the end.  For example: 5V cross section + 65″ outside length + 0 = 5V650.  Now you’ve got a good v-belt part number!


A,B,C, D, and E belts are slightly more complicated.  Their part numbers actually signify the inside diameter and not the outside diameter.  The inside diameter is easily obtained, however, by simply subtracting a pre-determined factor for each cross section.  Note the list below.


  • A belt – 2″
  • B belt – 3″
  • C belt – 4″
  • D belt – 5″
  • E belt – 7″

So for a B section belt + 65″ outside – 3″ = B62.



If the belt has cogs or teeth cut or molded into the inside of the belt, add an X after the cross section designation.  Examples: BX62 or 5VX650.


If you have multiple belts that have been banded or sometimes called ganged into one belt, put the number of belts followed by a “/” in the front of the number.  A 3 band belt might look something like 3/B62 or 3/5VX650.


*Note, v-belts are flexible rubber.  Because of this it can be easy to make a mistake while measuring so always double check.  In addition, belts can wear and stretch in a number of different ways depending on how they have been used.  If you are unsure of your measurements, call, e-mail, or come into our service counter.