Matching Neck Finishes

You spent a non-trivial amount of time finding the right container for your product. Good shape, right size, looks exactly how you imagined it on your shelf. You’re ready to order. Then the listing mentions a neck finish, and suddenly you’re staring at something like 24-410 wondering if you accidentally wandered into a hardware catalog.

You didn’t. And it’s not as complicated as it looks. But it does matter, because the wrong lid means a cap that wobbles, leaks, or refuses to close.

Here’s how the whole “neck finish” thing works.

What is a Neck Finish?

A neck finish is just the opening of your container, defined by its diameter, height, and thread style. Those three things together determine which lids will fit properly.

The code you see in product listings (like 24-410 or 18-400) is a shorthand for those measurements:

• The first number is the diameter of the opening in millimeters
• The second number describes the thread style and how many times the threads wrap around the neck

A 24-410 container needs a 24-410 lid. This isn’t a case of “oh well close enough.” They need to be the same number.

Two Types of Threads: Continuous vs. Twist

Before you measure anything, it helps to know which of two basic thread categories you’re working with.

Continuous thread (CT) is the classic screw-on lid, featuring one long thread that spirals around the opening. This will be on your peanut butter jar or your morning juice bottle. You’ve been using these your whole life; you just didn’t know what they were called. Now you do. What a momentous occasion. The thread style is indicated by the three-digit code (400, 410, etc.).

Lug or twist finish (TW) has multiple short threads that only go partway around, and the lid snaps shut in about a quarter turn. There’s a small latch that holds under pressure. This will pickle jar. Think jam. Lug finishes are marked TW in the neck finish code, they’re not compatible with continuous thread containers, so it’s worth knowing which one you have before you start comparing lids.

How to Measure Your Neck Finish

Grab calipers if you have them (they’re about $10 and genuinely useful if packaging is now part of your life). A ruler works too. If you’re feeling adventurous, you can print our Neck Finish Measurement tool here. Make sure to print at 100% scale, cut the red outline, and tape the two halves together. It works, just don’t plan on showing it off at any craft fairs.

To measure your container: measure from the outermost edge of one thread, straight across through the middle, to the outermost edge on the other side. Include the threads, don’t just measure the hole in the center. That part trips people up.

To measure your lid: measure from inner wall to inner wall. Not the outside of the cap — the inside.

Either way, your number is in millimeters. That’s the first number in your neck finish code. In the example above, it would represent the 28 in 28/410.

Identifying the Style and Threads

Next, take note of the thread style and how many times the threads pass one another to determine the last number (or letters) in your “Neck finish.”

• Example one: 28mm measurement of the lid and container and 1.5 thread turn, equals 28-410 Neck Finish
• Example two: 70mm measurement of the lid and container with a LUG turn (.25 of a full turn), equals 70TW Neck Finish

Below is a list of the common neck finish threading styles.  

Put it together: a container that measures 28mm across with threads that wrap 1.5 times is a 28-410 neck finish. A 70mm lug finish is 70-TW. The system is actually pretty logical once they’re able to be deciphered.

Time to Say Goodbye

If your container is already on containerandpackaging.com, there’s an easier path: look for the Matching Items section on the product page. Every container shows its compatible closures directly, no math required.

And take advantage of our sample program. You can order up to 10 different lids or containers to test-fit before you commit to a full run. Getting it right at the sample stage costs you almost nothing. Getting it wrong at 500 units is how core memories are made.

This will most definitely shock you: a blog post on containerandpackaging.com is suggesting you shop at containerandpackaging.com. Take a moment. Then go find your lid, we’ve got a lot of them.

Questions? A real human is standing by: (800) 473-4144