The Ultimate Guide to Capsule Sizes: From Size 000 to Size 5

Introduction

In the dietary supplement industry, the delivery system is just as critical as the active ingredients. While the formula defines the benefit, the capsule size defines the experience. Choosing the correct shell is a strategic balancing act: you must ensure the capsule has enough volume to hold your target dosage (mg) while remaining small enough to guarantee consumer compliance and easy swallowing.

Table of Contents

The global pharmaceutical and supplement industries utilize a standardized numerical scale to classify these dimensions. This spectrum is vast, ranging from the massive size 000 capsules (currently the largest capsule size available for standard human consumption) all the way down to the microscopic size 5 capsules, which are typically reserved for pediatric use or highly potent active pharmaceutical ingredients (APIs).

This standardization applies regardless of the material. Whether you are using traditional gel capsule sizes (Gelatin) or modern vegetarian (HPMC) shells, the external dimensions and locking mechanisms follow the same international specifications.

In this comprehensive guide, we will break down the technical specifications of every option. We will explore the capsule size chart in detail, compare the popular Size 0 vs. 00, and explain how powder density impacts the actual milligram (mg) capacity of your product.

The Complete Capsule Size Chart (mg & ml)

Navigating the technical specifications of capsules can be confusing. To help you make the right formulation decision, we have compiled the essential data into this master reference table.

This capsule size chart covers the physical dimensions (length and volume) and the estimated weight capacity for both standard gel capsule sizes and vegetarian alternatives.

Please note that the milligram (mg) capacity listed below is an estimate based on a standard powder density of 0.8 g/ml. If your powder is fluffier (lower density) or denser, the actual weight will vary.

📏 Capsule Dimensions & Capacity Table

Capsule Size	Volume (ml)	Locked Length (mm)	Weight Capacity (mg)(at 0.6 g/ml density)	Weight Capacity (mg)(at 0.8 g/ml density)	Weight Capacity (mg)(at 1.0 g/ml density)
Size 000	1.37 ml	26.14 mm	822 mg	1096 mg	1370 mg
Size 00	0.95 ml	23.30 mm	570 mg	760 mg	950 mg
Size 0	0.68 ml	21.70 mm	408 mg	544 mg	680 mg
Size 1	0.50 ml	19.40 mm	300 mg	400 mg	500 mg
Size 2	0.37 ml	18.00 mm	222 mg	296 mg	370 mg
Size 3	0.30 ml	15.90 mm	180 mg	240 mg	300 mg
Size 4	0.21 ml	14.30 mm	126 mg	168 mg	210 mg
Size 5	0.13 ml	11.10 mm	78 mg	104 mg	130 mg

🔍 Key Technical Notes:

Size 00 Capsule Dimensions: As shown above, the Size 00 is approximately 23.3 mm long when locked. This is a critical metric for bottle sizing—if your capsule is too long, you may need a larger neck finish on your packaging.
Capsule Size Chart mg: The “mg” column is the most variable. A capsule size chart mg value is never a guarantee; it is a calculation. For example, a fluffy herbal extract might only fill 600mg into a Size 00, while a dense mineral blend could fit nearly 1000mg.

High-Volume Capsules: Sizes 000 & 00 (For Maximum Potency)

When your formulation requires a high dosage (over 600mg per pill) or involves fluffy, low-density powders (like herbal leaves), standard capsules simply won’t fit the material. This is where high-volume shells come into play.

Size 000 Capsules – The Largest Capsule Size

Size 000 capsules hold a unique position in the market. They are widely considered the largest capsule size available for standard human oral consumption.

Capacity: With a massive volume of 1.37 ml, a single Size 000 capsule can hold anywhere from 800mg to 1300mg of powder, depending on density.
Best Applications: These are the go-to choice for bodybuilding supplements (like BCAAs or Creatine) or bulky herbal fibers where the consumer is willing to swallow a large pill to avoid taking 3-4 smaller ones.
The Trade-off: The sheer size (over 26mm long) makes them difficult for many people to swallow. They are generally not recommended for multivitamins targeting the elderly or children.

Size 00 Capsules – The Industry Standard for High Dosing

If Size 000 is the “giant,” then size 00 capsules are the “heavyweight champions.” They are currently the most popular choice for high-potency supplements globally because they strike a better balance between volume and swallowability.

Capacity: A Size 00 capsule holds approximately 0.95 ml. For most standard supplement blends, this equates to a fill weight of 600mg to 750mg.
Size 00 Capsule Dimensions: It is crucial for packaging engineers to note the size 00 capsule dimensions: roughly 23.3 mm in locked length and 8.5 mm in diameter.
Why Brands Choose It: It allows for a “2-pill per day” serving size for many formulas that would otherwise require 4 pills if using smaller sizes. This efficiency makes size 00 capsules a favorite for Magnesium, Glucosamine, and complex herbal stacks.

Medium & Standard Capsules: Sizes 0 & 1 (The Consumer Favorites)

While “bigger is better” for potency, “smaller is better” for the consumer experience. This middle range represents the sweet spot for most successful commercial supplement brands.

Size 0 Capsules – The Most Common Choice

If you pick up a standard multivitamin or antibiotic from a pharmacy shelf, chances are it is a size 0 capsule.

The “Goldilocks” Size: Size 0 capsules are widely regarded as the industry standard for general supplements. They are significantly easier to swallow than the bulkier Size 00, yet they still hold a respectable volume (0.68 ml).
Capacity: You can typically fit 400mg to 500mg of powder into a Size 0 shell. This makes it perfect for ingredients with moderate daily dosages, such as Vitamin C or complex herbal blends where the serving size is 2-3 capsules.

Capsule Size 0 vs 00: Which One Should You Choose?

This is the most frequent question we receive from brand owners: Capsule Size 0 vs 00—which is better?

The decision comes down to a trade-off between Volume and Compliance:

Volume Difference: Size 00 capsules hold approximately 40% to 50% more powder than Size 0. If your formula requires 1500mg per day, using Size 00 means the consumer takes 2 pills; using Size 0 might require 3 or 4 pills.
Swallowability: Size 0 is the clear winner for user experience. If your target demographic is sensitive to pill size (e.g., elderly populations), forcing them to swallow a large Size 00 may result in poor product adherence.

Our Recommendation: Start with Size 0 capsules if your formula fits. Only upgrade to Size 00 if the pill count becomes unreasonable (e.g., asking a user to take 4+ pills per day).

Size 1 Capsules – Great for Moderate Doses

Moving slightly down the scale, size 1 capsules offer a sleek, compact profile.

Dimensions: With a locked length of roughly 19.4 mm, they are very easy to swallow.
Capacity: Holding about 300mg to 400mg, size 1 capsules are excellent for potent ingredients that don’t require fillers.
Best Application: They are frequently used for pure single-ingredient products (like specific B-Vitamins, Zinc, or concentrated extracts) where using a larger Size 0 shell would require adding unnecessary bulking agents just to fill the space.

Small & Specialty Capsules: Sizes 3, 4, & 5

While large capsules dominate the sports nutrition aisle, there is a crucial market for precision dosing. These smaller sizes are essential for high-potency ingredients, pediatric formulations, and veterinary applications.

Size 3 Capsules – Precision Dosing

Size 3 capsules represent the entry point into “small” capsules.

Capacity: With a volume of 0.30 ml, they typically hold 150mg to 200mg of powder.
Best Application: You will often find size 3 capsules used in clinical trials (double-blind studies) or for ingredients that require smaller, more frequent doses to maintain steady blood levels. They are also popular for expensive, high-potency herbal extracts (like Saffron or pure Resveratrol) where the active dose is low, and a larger shell would look “empty.”

Size 4 Capsules – Pediatric & Veterinary Use

As we go smaller, size 4 capsules become a niche but vital tool.

Dimensions: These shells are significantly shorter (approx. 14.3 mm locked length) and thinner than standard capsules.
Best Application: Their compact size makes them ideal for populations with difficulty swallowing (dysphagia), such as children or the elderly. Additionally, size 4 capsules are a favorite in the veterinary compounding industry for dosing small pets (cats and small dogs) who cannot ingest a standard Size 0 pill.

Size 5 Capsules – The Smallest Capsule Size

Finally, we reach the limit of standard manufacturing. Size 5 capsules are recognized as the smallest capsule size available for commercial filling machines.

Capacity: Holding only about 0.13 ml (roughly 75mg to 100mg), these are microscopic compared to a Size 000.
Usage: You won’t see size 5 capsules on a supermarket shelf. They are almost exclusively used for:
1. Micro-dosing: Extremely potent active pharmaceutical ingredients (APIs).
2. Pet Medicine: For very small animals where even a Size 4 is too large.
3. Capsule-in-Capsule Technology: Sometimes a Size 5 capsule (containing liquid or incompatible ingredients) is placed inside a larger Size 00 capsule to create a dual-release system.

Understanding Powder Density: Why “mg” Varies?

One of the most common frustrations for new supplement brands is selecting a capsule based on a capsule size chart mg column, only to find out during production that their powder doesn’t fit.

Why does this happen?

The Rule of Physics:

Capsule Volume (ml) is Fixed. Powder Weight (mg) is Variable.

A Size 00 capsule will always hold 0.95 ml of volume. However, how much weight (mg) fits into that 0.95 ml depends entirely on the Density of your powder.

The “Feathers vs. Lead” Analogy

Think of it this way: A bucket (fixed volume) can hold 10kg of rocks, but that same bucket might only hold 1kg of feathers.

High Density (Heavy): Ingredients like Minerals (Calcium Carbonate, Zinc Oxide) or crystalline salts. These are like rocks. You can fit a massive amount of weight into a small shell.
Low Density (Light/Fluffy): Ingredients like Herbal Leaf Powders (Moringa, Alfalfa) or fine Botanical Extracts. These are like feathers. They take up a lot of space but weigh very little.

Bulk Density vs. Tapped Density

When reading a capsule size chart, the “mg” capacity is typically calculated using a standard density of 0.8 g/ml. But in the real world:

Bulk Density: The volume the powder takes up when it’s just sitting in a bag (lots of air).
Tapped Density: The volume the powder takes up after being vibrated or “tamped” down in the capsule filling machine. This is the number that matters.

Real-World Example:

Ingredient A (Dense Mineral): 1000mg might fit easily into a Size 00 capsule.
Ingredient B (Fluffy Herb): You might struggle to fit even 500mg of this into the exact same Size 00 capsule.

Pro Tip for Formulators: Never rely solely on a generic chart. Always measure the Tapped Density of your specific blend before ordering millions of empty capsules. If your density is low (e.g., 0.4 g/ml), you will likely need to upgrade to a larger size (e.g., move from Size 0 to Size 00) to hit your target dosage.

How to Choose the Right Size for Your Product? (Step-by-Step)

Selecting the correct capsule size is not a guessing game; it is a calculation. Follow this 4-step framework to ensure your product is manufacturable and consumer-friendly.

Step 1: Calculate Your Total Formulation Weight

First, determine the total weight of active ingredients plus any necessary excipients (flow agents, fillers) for a single dose.

Example: You need 500mg of Ashwagandha + 10mg of flow agents = 510mg Total.

Step 2: Measure Your Tapped Density

As discussed in the density section, don’t guess. Send your powder to a lab or use a graduated cylinder to find the Tapped Density.

Formula: Total Weight (mg) ÷ Tapped Density (mg/ml) = Required Volume (ml).
Example: 510mg ÷ 0.75 g/ml = 0.68 ml.

Step 3: Consult the Capsule Size Chart

Look at the Volume (ml) column in our capsule size chart above. Find the size that fits your calculated volume.

Result: Size 0 holds 0.68 ml. This is a perfect match.
Decision: If the calculation was 0.80 ml, you would need to upgrade to size 00 capsules.

Step 4: Consider the Demographic (The “Swallow Test”)

Before finalizing, ask: Who is taking this?

Bodybuilders: They will tolerate size 000 capsules or size 00 for high potency.
General Public: Size 0 is the safest bet for maximum compliance.
Children / Elderly: If the math says Size 00, consider splitting the dose into two size 1 or size 3 capsules to prevent choking hazards.

fAQs

What is FAQWhat size capsule holds 1/4 teaspoon??

Size 000 is the closest match. A standard 1/4 teaspoon equals approximately 1.23 ml.
Size 000 has a volume of 1.37 ml, which comfortably holds a level 1/4 teaspoon of powder.
Size 00 (0.95 ml) is too small to hold a full 1/4 teaspoon. If you are filling capsules at home using measuring spoons, Size 000 is your best option.

Which capsule size has the largest capacity?

For standard human consumption, Size 000 is the largest available size. It holds approximately 800mg to 1300mg (0.8g to 1.3g) of powder, depending on density. While larger veterinary sizes exist (like Size 11 or 13 for large animals), Size 000 is the upper limit for standard supplement manufacturing machinery.

How are capsules sized?

Capsules are sized using a reverse numerical scale. The smaller the number, the larger the capsule.
000 = The Largest.
00 = Very Large.
0 = Standard (Medium/Large).
1, 2, 3, 4 = Small to Very Small.
5 = The Smallest.

How big are size 0 capsules?

A standard Size 0 capsule dimensions are:
Locked Length: Approximately 21.7 mm (0.85 inches).
External Diameter: Approximately 7.6 mm.
Volume: 0.68 ml. It is roughly the size of a standard peanut. It is considered the most balanced size for ease of swallowing vs. filling capacity.

How many capsule sizes are there?

There are 8 standard sizes used globally for pharmaceuticals and supplements. They range from Size 000 (largest) to Size 5 (smallest). The full sequence is: 000, 00, 0, 1, 2, 3, 4, and 5.

How many grams does a size 0 capsule hold?

A Size 0 capsule typically holds between 0.4 grams and 0.5 grams (400mg – 500mg) of standard density powder.
Important Note: It rarely holds a full “1 gram.” To fit 1 gram (1000mg) of powder, you would generally need a significantly larger Size 000 capsule or a very dense material. Always check your powder’s density, as “grams” measure weight, not volume.

Conclusion

Whether you are formulating a high-dose sports supplement requiring the largest capsule size (Size 000) or a potent micro-dose requiring the smallest capsule size (Size 5), understanding the physical dimensions is critical to your brand’s success.

The right capsule size does more than just hold ingredients; it defines your manufacturing costs, packaging requirements (bottle size), and ultimately, your customer’s satisfaction.

Take the Next Step Don’t rely on generic estimates. Whether you are using standard gel capsule sizes or HPMC vegetarian shells, we recommend requesting a sample kit to test your specific powder density.

Need a broader overview? For a deeper dive into materials, manufacturing processes, and market trends, read our Capsule Supplements Comprehensive Guide.
Ready to manufacture? Contact our technical team today to match your formula with the perfect shell.

Resource

U.S. Food and Drug Administration (FDA)

ScienceDirect

NIST