How To Measure Chain Size? Click For The Complete Guide

Getting the chain of the right size for your project will save a lot of time and money. Yet, measuring it will be challenging due to its complicated structure. 

So how to measure chain size correctly? We will share some tips to pull it off. Let’s stay with us till the end! 

How To Measure Chain Size? 

How to Measure Chain Size

Using a pair of calipers while measuring a chain is advisable to guarantee that your measurements are accurate. Here is how to measure the chain size using the calipers:

  • Measure the pitch, which is the distance between the center of a pin to the next. Also, measure the pin diameter. 
  • Next, move to the plate height. You can measure the outside or inside height, but they should match. If they are different, it means that you don’t have a standard chain. 
  • Measure the plate thickness outside and inside. Some ISO chains have outside and inside plates with different thicknesses. 
  • You need to identify the overall width of the chain, which is the distance between two opposing pins. 
  • You should also know the number of links by looking at the chain and counting the links.

There is some confusion regarding bike chain sizes because there are two standards, the ANSI (American National Standards Institute) and the ISO (International Organization for Standardization), to measure chain size.

ANSI chains use inches as measurement units; some standard sizes are 25, 42, 40, etc. Meanwhile, although ISO often uses metric measurements, it measures chains in inches too. 

If you have measured your vehicle chain and the numbers do not match any ANSI standard, you may use an ISO chain.  

You can check the chain size of your vehicle by reading the owner’s manual. It comes in a two- or three-digit number. This chart will show you some popular choices of chain size:

Chain size Pitch size (inches) Inside width (inches)  Standard
25 1/4 1/8 ANSI
35 3/8 3/16 ANSI
40 1/2 5/16 ANSI
41 1/2 1/4 ANSI
415 1/2 3/16 ISO
420 1/2 1/4 ISO
520 5/8 1/4 ISO
530 5/8 3/8 ISO
630 3/4 3/8 ISO


1. How do I know my chain size?

The plates often have the chain size marked on them. You can use the information given by the manufacturer to search out the dimensions of the chain in detail. If not, you should read the owner’s manual, which usually mentions both the chain size and the number of links needed.

If you can’t find the number of links on the manual, check your chain and count them.  

2. What do chain size numbers mean?

Chain size is a three-digit number (based on ISO standards). The first digit refers to the pitch size, while the other two are the width. 

These numbers are in eighths of one inch. For example, if the size of the chain is 520, you can refer to two things:

  • Pitch: 5 x 1/8 = 5/8″
  • Inside width: 2 x 1/8 = 2/8″

3. What is the most common size chain?

40, 50, and 60 classes are the most common choices. The differences between them are as follows:

  • 40 class: Pitch = 0.5″ and Width = 0.312″
  • 50 class (520 and 530): Pitch = 0.625″ and Width = 0.375″ or 0.250″
  • 60 class (630): Pitch = 0.750″ and Width = 0.375″

4. Is a thin or thick chain better?

Although thicker chains will add more weight to your vehicle, they offer higher security and stability. Hence, we suggest going for the thick. 


Since the chain is too small, you need calibers for the most accurate results. Then, take each measurement carefully, following our guide. 

Hopefully, you will find this article helpful. Please let us know if you have any problems while measuring the chain size. We are always ready to help.

Thank you for reading, and see you in the next post! 

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