What timing belt do I need?

Have you ever been in the situation where you need to buy a timing belt but don’t know the reference number?

With so many references and so little information available or printed on the belts, sometimes is hard to know the reference of the one that you need. Then you spend more time figuring out what you need so you can look for the part or call your supplier, and an easy buy became a total piece of work.

We have compile a little guide to help you with that

First of all, make sure it’s a timing belt, otherwise, go to the v-belt selection guide. A timing belt will have teeth on the inside (or both sides if its a double sided timing belt) and it will be kind of a flat belt.

V-Belt – Not a Timing belt
Timing Belt






Double Sided Timing Belt
Cogged Belt- Not Timing belt







Now that you know it’s a timing belt for sure, let’s go in to details. If you have a double sided belt, just pretend is a regular timing belt until the end of this blog.

Sometimes you will find that the part is printed on the belt, and it will be something like 2388-3M, then you are lucky and you are just missing one number at the end which will determine the width of the belt. We will talk about it in a moment.

The first step is to determine the pitch, which is the distance between teeth centers


Once you identify this, please go to the chart below:

MXL 0.080″
XL 0.200″
L 0.375″
H 0.500″
XH 0.875″
3M 3 MM
5M 5 MM
8M 8 MM
14M 14 MM

We already have part of the belt reference. Let’s proceed. To get the length, you can either take the pitch length which is the length of the belt in the middle part, a little tricky to get, or you can count the number of teeth and multiply it by the pitch. For example, let’s say you have a 8M timing belt with 73 teeth. If you multiply 73*8 (which is the pitch: 8mm), you will have that your belt length is 584 mm. The length has to be in the same units of measure than the pitch, that is mm in this case or inches for the first 5 types in the chart above.

Now that we’ve got this far, the belt so far is a 584-8M

To find out the last part, you need to measure the width of the belt, again, in the same units of measure than the pitch. Lets say we need the belt to be 50 mm wide.

The complete reference number is 584-8M-20

We are always happy to help, leave your comments or contact us if you need help with your timing belt