The Bottle Jar Store is a one-stop-shop for a great variety of jars in all shapes and sizes. However, we also sell closures that you can either purchase alongside your glass jars or separately in quantities from one all the way up to thousands.

When it comes to jam jar lids, it can be tricky (and sometimes frustrating) to work out the exact size you need. There is a range of considerations needed to ensure the lid fits perfectly, and the last thing you want is a pile of closures that don’t effectively secure the contents of your jar.

Don’t worry, though, we’re here to guide you through measuring your jam jar lids correctly.

Continuous Thread (CT) Vs Lug (Twist-Off)

There are two main types of jar (and therefore jar lids) which are not interchangeable, so it’s important you know which is which. Continuous thread is typically used for mason jars, spice jars or even medication. However, those used in the last example are also adapted so that they need to be pushed down as well as twisted when opened.

One of the easiest ways to tell if a lid is for a continuous thread jar is that it requires a full turn and a half for it to come off. In contrast, twist-off lids only need to be rotated a quarter of a turn before they can be removed. You can also take a look at the underside (skirt) of the lid to check for ‘lugs’, small indents that help it lock into place on the jar, which you can see in the image below.

Twist-off, or lug, closures are used across a wide variety of jars including sauces, jams and other food and beverage products. One final way to tell the difference between these and CT jars is to look at the rim. As the name suggests, continuous thread jars feature a straight, unbroken bead around the opening, whereas the rim of a lug jar has a broken thread which is slanted at a slight angle.

Types Of Twist-Off Jar

If you’ve established that you need twist-off lids, you will then have to consider the depth of the mouth at the top of the jar. There are many types of finish that the jar could have, including Angle Flat, which is used to protect the lid from being over-screwed, and PT (push-on, twist-off), which is mainly used for baby food.

However, the most common finish (area between the shoulder and the lip) for a twist-off jar is a Helix, which can either be 7mm (Regular), 14mm (Deep) or 18mm (Extra Deep). To determine which of these you need, you can simply measure with a ruler.

Measuring Jam Jar Lids

If You Already Have a Lid

If you have a lid that you know fits your jar and you just need to order more, you can set it upside down on a flat surface and measure from the skirt to the top to find out the depth. Keep in mind that jar lids are measured in millimetres, so you’re looking to see whether you’ll need regular, deep or extra deep according to the specifications above.

Armed with the correct measurements for the depth, you can then work out the size of the lid you will need. To do this, place your ruler across the widest part of the lid and make note of the diameter. It may be difficult to get this exactly right but, handily, there are standard sizes that can offer some guidance: 38, 43, 48, 53, 58, 63, 66, 70 and 82 millimetres. Whichever figure is closest will be the size of the lid you need.

If You Don’t Have A Lid

The process for deciphering which size lid you need if you only have the jar is very similar except you will need to measure the diameter of the rim instead. Place your ruler from one side of the glass to the other, at the widest point. Something to keep in mind is that the lids are always one or two millimetres bigger than the jar opening, so when you’re measuring the glass you will need to add this on to find the size of the lid needed.

Finally, to calculate the depth of closure required when you don’t have a lid to work with, you can measure from the top of the jam jar’s shoulder to the rim. This will give you an idea of whether you need a regular, deep or extra-deep lid.

Now that you know how to correctly determine which closures you need, head over to our jam jar lids page to check out the different options we have available. As well as varying sizes and depths, we also have a great range of colours to help match your brands and products.

About the author : Amanda Hallinan

Related posts