Everything you ever wanted to know about neck finishes
neck finish
Whether you’re talking about plastic bottles, glass bottles, PET jars, plastic pill bottles or other types of containers, you often hear the term neck finish, but, what exactly is it?
 
 

The neck is the upper part of the bottle that accommodates the cap, the lid, the dosing pump, the trigger sprayer or the dispensing sprayer.
 

The closure must have the same neck finish as your bottle, jar or other container to make sure it doesn’t leak.
 

To make sure you get a compatible closure for your container, choose one of the lids shown at the bottom of the page of the container you’ve selected.

 

 

 

What is a neck finish?

 

 

A neck finish is defined by a number of dimensions, including:

  • the height,
  • its inner diameter
  • its outer diameter
  • the thread, for containers with screw-on lids


The dimensions are always expressed in millimetres.

 

 

neck finish

 

 

 

 

Understanding neck finish sizes

 

20/410, 24/415, 28/410, neck finishes...

 

 

CGMI neck finishes, corresponding to US standards, are very common.


These neck finishes are composed of two numbers separated by a fraction bar, for example: 28/410 or 28/400.

 

  • The 1st number (for ex. 28) is the OUTER DIAMETER of the neck in mm
     
  • The 2nd number (for ex. 410) refers to the thread configuration and height of the neck.

 

 

 

18DIN, 28DIN, neck finishes...

 

Another common type of neck finish designation is formatted as follows:


 

  • The first number indicates the OUTER DIAMETER of the neck
     
  • It is always expressed in millimetres
     
  • The letters DIN after the number are short for "Deutsches Institut für Normung"

 

 

 

Some points to watch

 

All the dimensions must match. For instance, if the height of the neck finish on the container and the lid is not the same, the container will not be leak-proof.

 

Beware of "false friends": Some necks have commonalities or similarities that can be misleading, so be careful (for example, a neck finish of 24/410 and a neck finish of 28/410 do not match).

 

Finally, on some closures, other elements must be considered. For example for plastic screw caps with a bore seal or for flip-top caps, the sealing lip must perfectly match the inner diameter of the neck.
 

In addition, for reducer applicator caps,  if the neck diameter is too large, the reducer won't fit and the seal will not be ensured. So it’s important to choose an accessory that matches the container you’ve selected.