How Big is a Bottle Cap?

If you want your fizzy drink to stay fizzy for longer, you’ll have to place the cap back on the bottle. It will also prevent dust and other contaminants from getting in your drink and ruining your day. But have you ever thought about the dimensions of a bottle cap?

The typical bottle cap will have an exterior diameter of around 30 millimeters, an interior diameter of 28 millimeters, a pitch of around 4 millimeters, and a height of 5.5 millimeters. However, bottle cap sizes are usually expressed in terms of exterior diameter and bottle neck finish.

In this guide, I’ll explain the basics of bottle cap sizes, common bottle cap sizes and the dimensions of various bottle caps used in popular products, and the different bottle cap variants.

Basics of Bottle Cap Sizes

Bottle caps and the neck of a bottle go almost literally go hand in hand. Whether a bottle cap can be used to shut a bottle will be determined by whether or not it fits around the bottle’s neck. So, when looking at bottle cap sizes, it’s always in relation to the bottle’s neck finish.

Bottle cap sizes will be expressed in 2 numbers—e.g., 28-410. The first number, 28 in this case, refers to the interior diameter of a bottle cap or the exterior diameter of the bottle’s neck. The second number is the neck’s thread finish per GPI standards.

Measuring Neck Finish

When looking at neck finishes, there are 5 variables you have to keep in mind. All of these variables are required to know the technical specs of an appropriate bottle cap.

T-Dimension = The exterior diameter of the neck’s threads

I-Dimensions = The diameter of the bottle neck’s opening

E-Dimensions = The distance between the interior of the bottle cap and the exterior diameter of the neck’s threads

S-Dimensions = The distance between the top of the bottleneck and the topmost thread

H-Dimensions = The height of the bottleneck

Types Neck Finishes

Below are some of the most commonly used neck finishes.

410—Single-thread turn

410—1.5 thread turns

415—2 thread turns for tall caps

425—2 thread turns for narrow caps

430—Single-thread turn with thicker threads

2000—Non-continuous threads

Bottle Cap Sizes

There could be dozens of different bottle cap sizes depending on where you source them. For instance, the folks at Midwest Bottles offer 15-size options. I’ll list some of the more widely used sizes below and include the types of products that use them.

Types of Bottle Caps

While there is a finite number of bottle cap sizes to choose from, bottle cap varieties are virtually limitless. As such, I’ll list and explain only some of the most commonly used bottle caps you’ll find in stores. It’s important to note that each type of bottle cap can come in a variety of different sizes, so you should still consider the cap’s size figures.

Tamper-Evident Bottle Caps

Also known as a tamper-evident band, this bottle cap is made of aluminum and is fastened into place around a ring. When you twist the cap open, you sever the connections between the cap and the ring, but the ring will stay in place at the base of the neck. You’ll mostly find this type of bottle cap on syrup bottles.

Plastic Tamper Bottle Caps

This is identical to tamper-evident bottle caps, except it’s made of plastic. You’ll notice whether or not the bottle cap has been twisted open if the plastic connections between the security ring and the cap have been broken. Soda bottles use this type of bottle cap.

Bottle Caps with Brushes

There are bottle caps that have brushes on the underside. You can use the integrated brush to take and apply some of the bottle’s contents. This is typically used in glue bottles.

Dispenser Bottle Caps

This type of bottle cap has an integrated dispenser mechanism that, when depressed, will suction a bit of the bottle’s contents and dispense it through a nozzle. You’ll most often find this type of cap on hand soap and lotion bottles.

Bottle Caps with a Foam Liner

If you’ve ever cracked open a bottle of engine oil, you’ve probably noticed a foam disc on the underside of the cap. That disc is made of foam and serves to protect the plastic cap from chemicals that could possibly leak out of the cap or cause it to deteriorate.

Domed Bottle Caps

The top portion of the bottle cap has a slight dome to it, giving the bottle a slightly elegant appearance. Makeup jars will usually have a domed cap.

Bail-Wire Swing Top

This type of bottle cap consists of a plastic plug and a metal clasp. When the plug is inserted into the bottleneck, you can bring the clasp down to push the plug deeper into the neck, preventing air from getting into the bottle. Glass water bottles will use this type of bottle cap.

Lidded Bottle Cap

Some bottles will have built-in lids that swing up and down. That way, you can open and shut the bottle without having to twist off a cap.

Sports Bottle Cap

This is the bottle cap that you will find on Gatorade bottles. By tugging on the cap, you will release the lid to allow the beverage to come out with a gentle squeeze.

Metal Crown Bottle Caps

This bottle cap requires a bottle opener to remove. When in place, it vacuum-seals the contents of the bottle. Removing the bottle cap creates a satisfying sound of air rushing into the bottle, as well as a slight puff of smoke. Glass soda and beer bottles use metal crown bottle caps.

Spray Bottle Caps

There are 2 types of spray bottle caps—the type that you push down and the type with a trigger that you squeeze. Both spray bottle cap types are used to dispense a tiny amount of the liquid inside the bottle. Each squeeze will send the contents in a wide fan. Windex and perfume bottles will use different variations of spray bottle caps.