Screw Lotion Pump Sizes Explained: 24/410, 28/410, and More

Quick Answer: Understanding Screw Lotion Pump Sizes

Screw lotion pump sizes are labeled using a two-number system like 24/410 or 28/410. The first number (24, 28, etc.) is the outer diameter of the bottle neck opening in millimeters, and the second number (410) refers to the thread finish — essentially the thread pattern and depth that determines how many turns are needed to screw the pump on securely. To find the right pump, you simply need to match both numbers to your bottle's neck specifications; if either number doesn't match, the pump won't thread on correctly, even if it looks similar in size.

The most common sizes for lotion, shampoo, and soap bottles are 20/410, 24/410, and 28/410, covering the vast majority of standard retail and travel-size containers.

How the Numbering System Actually Works

The sizing format follows an industry-standard convention used across the packaging industry, not just for lotion pumps but for caps, sprayers, and dispensers in general.

The First Number: Neck Diameter

This number represents the outer diameter of the bottle's threaded neck, measured in millimeters. A "24" means the neck measures approximately 24mm across at its widest threaded point. Common values include 18, 20, 24, 28, and 33.

The Second Number: Thread Finish

The "410" refers to a specific thread type standardized by the packaging industry (SPI, the Society of Plastics Industry). It defines the thread pitch, number of thread starts, and depth. 410 and 400 finishes are the two most common for lotion and cosmetic pumps, with 410 being slightly more prevalent for pump-style dispensers.

Common Screw Lotion Pump Sizes and Their Uses

Below is a breakdown of the most frequently used sizes and where you'll typically find them.

24/410 is by far the most widely used size in the personal care industry, which is why it's often the default option stocked by most pump manufacturers and retailers.

How to Measure Your Bottle for the Correct Pump Size

If you don't know your bottle's size, you can determine it accurately at home with a simple measurement.

1. Use a caliper or ruler to measure the outer diameter of the bottle neck opening, right at the top of the threads.
2. Round the measurement to the nearest standard size (18, 20, 24, 28, or 33mm).
3. Count the number of separate thread starts around the neck — most 410 finishes have two thread starts, while 400 finishes typically have one continuous thread.
4. If unsure about the thread finish, try screwing on a pump you already have with a known size — a snug, smooth fit confirms a match.

Without a caliper, a piece of string wrapped around the neck opening and measured against a ruler gives a reasonably accurate estimate — accurate to within about 1mm, which is usually sufficient to identify the correct size category.

Why Matching the Exact Size Matters

Using an incorrect or approximate size can cause more problems than it solves.

Leaking and Poor Seals

Even a 1-2mm mismatch in neck diameter can prevent the pump gasket from forming a tight seal, leading to slow leaks or air entering the bottle, which affects product freshness.

Cross-Threading Damage

Forcing a pump with the wrong thread finish onto a bottle can strip the threads on both the pump and the bottle neck, making the container unusable for refills.

Wasted Product

A loose or improperly seated pump can allow the dip tube to sit incorrectly inside the bottle, leaving a significant amount of unusable product at the bottom that the pump can no longer reach.

24/410 vs. 28/410: Choosing Between the Two Most Popular Sizes

Since these two sizes cover the majority of household lotion and cosmetic bottles, it's worth understanding when to choose each.

• Choose 24/410 for bottles under 12 oz, including most hand lotion, face cream, and travel-size dispensers.
• Choose 28/410 for larger bottles, typically shampoo, conditioner, or body wash containers over 8 oz, where a wider neck allows faster, smoother dispensing.
• If replacing a broken pump, always check the original packaging or the embossed number often molded into the underside of the bottle neck — manufacturers frequently print the size directly on the bottle.

Frequently Asked Questions

Are 400 and 410 thread finishes interchangeable?

No. Although they may look similar, 400 and 410 finishes have different thread depths and starts, so a 410 pump will not thread properly onto a 400 neck, and vice versa.

Can I use a 24/410 pump on a 28/410 bottle with an adapter?

Yes, universal bottle neck adapters are available for this exact purpose, though a properly matched size is always the more reliable long-term solution.

Where can I find the size printed on my bottle?

Check the underside of the bottle or around the neck threads — many manufacturers emboss the size directly into the plastic during production.