Disc Top Cap Sizes Explained: 20/410, 24/410 & 28/410 Compatibility

Introduction: Why “24/410” Is the Most Important Number on Your Bottle Specification

If you have ever ordered bottle caps and found they do not fit your bottles, you already understand why neck finish dimensions are non-negotiable. The numbers “20/410,” “24/410,” and “28/410” are not arbitrary — they define a precise mechanical interface between your bottle and closure. A 24/410 cap will NOT thread onto a 28/410 bottle, and forcing it creates stress cracks, leaks, and customer returns. Yet many first-time buyers select a cap size based on “what looks right” rather than what their bottle neck actually measures. This guide explains exactly what these numbers mean, which size fits which application, and how to verify compatibility before you order 10,000+ units.

Decoding the Numbers: What “24/410” Actually Means

The neck finish designation follows the Glass Packaging Institute (GPI) standard, now universally adopted for plastic bottles as well. The format is: [outer diameter in mm] / [thread finish code].

• The first number (20, 24, 28): The outer diameter of the bottle neck opening in millimeters. A 24/410 cap fits a bottle whose neck outer diameter is approximately 24mm.
• The second number (410, 412): The thread finish code. “410” indicates a single-start thread with 1.5 turns to close; “412” indicates a taller thread profile but also with a single-start configuration. The 410 finish is by far the most common in cosmetic and personal care packaging.

Critical tolerance: the neck outer diameter tolerance is typically ±0.3mm. A cap designed for 24.0mm nominal may not seal reliably on a 24.5mm neck — this is why cap and bottle should always be sourced as a matched pair or at minimum verified on the same physical sample.

Disc Top Cap Size Specifications: The Complete Table

At Sunshine Plastic, we stock disc top cap tooling for all four sizes: 20/410, 24/410, 28/410, and 28/412. The 24/410 and 28/410 are by far the highest-volume sizes, representing approximately 80% of global cosmetic packaging demand. Our Ningbo facility produces 300,000+ disc top caps per month across these sizes.

Size Selection: Which Cap for Which Bottle?

Cross-Compatibility: The Most Common Mistake in Sourcing

Many buyers assume that “around 24mm” is close enough. It is not. Here is what actually happens when you mix sizes:

• 24/410 cap on a 20/410 bottle: Cap is too loose; threads skip; no seal forms.
• 20/410 cap on a 24/410 bottle: Cap cannot thread on at all — the inner diameter is too small to engage the bottle threads.
• 24/410 cap on a 28/410 bottle: Cap sits on top of the neck but threads won’t engage; leaks immediately on inversion.
• 28/410 cap on a 24/410 bottle: Cap is visibly oversized; partial thread engagement at best; cross-threading is inevitable.

The only exception: 28/410 and 28/412 caps can sometimes interchange because the outer diameter is the same (28mm) — the difference is thread height. A 28/410 cap may partially engage on a 28/412 bottle (short engagement) and vice versa (tight fit). Always verify physically before committing.

Material and Finish Options by Size

How to Measure Your Bottle Neck (If You Already Have Bottles)

If you already have bottles and need matching disc top caps, measure these three dimensions with a caliper (not a ruler):

1. Neck outer diameter (OD): Measure across the crest of the bottle threads, not the neck wall below the threads. This is your “24” in 24/410.
2. Thread pitch: Measure the vertical distance between two adjacent thread peaks. For 410 finish, this should be approximately 2.5–3.0mm.
3. Thread turns: Count how many full rotations the thread makes around the neck. For 410 finish, this is typically 1.5 turns.

If these measurements match a standard size within ±0.3mm, the corresponding cap size should fit. If they do not match any standard, your bottle has a non-standard neck finish and will require custom cap tooling — budget an additional $3,000–$5,000 for mold development.

Ordering and Production Considerations

When ordering disc top caps, size is not the only variable. Here are the practical parameters:

• MOQ: 10,000 units per size per color (standard). Larger sizes (28/410, 28/412) may have slightly higher MOQ due to material consumption.
• Lead time: 20 days standard for stock sizes and colors; 25–30 days for custom Pantone color matching or closure finish customization.
• Sample availability: Free samples of all standard sizes (20/410, 24/410, 28/410, 28/412) within 3–5 business days.
• Color customization: All sizes available in any Pantone-matched color. Small MOQ surcharge for custom colors (typically 10–15%).
• Testing: Each production batch is cycle-tested for 5,000+ actuations and leak-tested with water fill inversion.

Conclusion: Get Your Samples Before You Commit

1. Measure your bottle neck precisely with a caliper — do not guess based on “it looks about 24mm.”
2. Request disc top cap samples in your target size (and one size up, one size down for comparison). Thread them onto your actual bottles, fill with your product, and test in real usage conditions.
3. If you are sourcing bottles and caps from different suppliers, require both suppliers to confirm thread compatibility against the same GPI standard specification in writing before production begins.

At Sunshine Plastic, we stock disc top caps in all four standard neck sizes and provide free samples within 3–5 business days so you can verify fit before ordering. Our technical team can also review your bottle drawings to confirm neck finish compatibility at no charge.

About the Manufacturer: Ningbo Shaoshuai Plastic Industry Co., Ltd. (brand: SUNSHINE) is a professional plastic closure and dispensing pump manufacturer based in Ningbo, Zhejiang, China. We specialize in disc top caps, flip top caps, screw caps, trigger sprayers, fine mist sprayers, lotion pumps, foam pumps, treatment pumps, and cream pumps. Available neck sizes: 20/410, 24/410, 28/410, 28/412, 33/410. Closure finishes: Smooth, Ribbed, Aluminum, UV, Water Transfer Printing, Bamboo. Material: PP, PP/PE, PET. Facility: injection molding workshop with automatic assembly and in-house QC laboratory. Quality: ISO 9001 certified; Non Spill characteristic; 5,000+ cycle testing per batch. Monthly capacity: 300,000+ disc top caps per month. MOQ: 10,000 units (per size/color). Standard lead time: 20 days. Sample policy: free samples within 3–5 business days; buyer covers express shipping. Payment: 30% T/T deposit, 70% before shipment. Export markets: North America, Europe, Southeast Asia, Middle East, South America. Website: sunshine-lotionpump.com.