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

What Capsule Size Should You Choose?

For most dietary supplement formulas, Size 0 and Size 00 are the two most practical capsule sizes.

A Size 00 capsule holds about 0.95 ml of powder volume and is often used for higher-dose formulas, such as magnesium, herbal blends, collagen support formulas, and sports nutrition products. Depending on powder density, it may hold roughly 570–950 mg of powder.

A Size 0 capsule holds about 0.68 ml and is usually easier to swallow. It is often the better first choice when your formula can fit within the available volume.

The key point is this: capsule volume is fixed, but fill weight is not. A capsule size chart can tell you the available space, but only your powder’s tapped density can tell you the actual mg capacity.

Key Takeaways

• Largest standard capsule size: Size 000
• Most common high-dose supplement size: Size 00
• Most consumer-friendly standard size: Size 0
• Smallest standard capsule size: Size 5
• Best way to choose: Calculate required volume using your formula weight and tapped density
• Most common mistake: Choosing a capsule based only on “mg capacity” without testing powder density

Introduction

Choosing the right capsule size is not just a matter of checking a standard size chart. For supplement brands, the right capsule size affects fill weight accuracy, swallowing experience, packaging design, production efficiency, and customer compliance.

A capsule has a fixed internal volume, but the actual mg capacity depends on the tapped density and flow behavior of your powder blend. That is why two formulas with the same target dosage may require different capsule sizes in real production.

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.

How to Use This Capsule Size Chart

Use the Volume (ml) column as your primary decision point. The mg values are estimates only because two powders with the same weight can occupy very different amounts of space.

To estimate the capsule size you need:

1. Add up the total formula weight per capsule, including active ingredients and excipients.
2. Measure or estimate the tapped density of the final blended powder.
3. Divide total formula weight by tapped density to calculate the required volume.
4. Choose the smallest capsule size that provides enough volume.
5. Confirm the result with a pilot fill test before full-scale production.

📏 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

Optional Elongated Sizes: 00E and 0E

Some manufacturers also offer elongated capsule sizes such as 00E and 0E. These are longer versions of standard capsules and provide slightly more filling volume without moving all the way up to the next standard size.

Capsule Size	Approx. Volume (ml)	Capacity at 0.6 g/ml	Capacity at 0.8 g/ml	Capacity at 1.0 g/ml	Best Use Case
Size 00E / 00el	1.02 ml	612 mg	816 mg	1,020 mg	When Size 00 is slightly too small but Size 000 is too large
Size 0E / 0el	0.78 ml	468 mg	624 mg	780 mg	When Size 0 is slightly too small but Size 00 may reduce swallowability

Elongated sizes can be useful for B2B formulation projects, but availability depends on capsule material, color, MOQ, and filling machine compatibility. Always confirm shell compatibility before ordering production quantities.

Key Technical Notes

• Capsule volume is the most reliable comparison metric. A Size 00 capsule has a fixed internal volume, but the actual mg capacity changes depending on powder density, particle size, flowability, and compression during filling.
• Do not treat mg capacity as a guaranteed number. The same Size 00 capsule might hold less than 600 mg of a fluffy botanical powder but close to 950 mg of a dense mineral blend.
• Locked length matters for packaging. Longer capsules may require a larger bottle neck finish, different count-per-bottle planning, or additional packaging validation.
• Material does not usually change the nominal size system. Gelatin, HPMC vegetarian, and pullulan capsules generally follow the same numerical size categories, but shell weight, moisture behavior, machinability, and supplier tolerances can differ.
• Always run a pilot fill test. Before ordering millions of empty capsules or printing packaging, test the actual blend on the intended capsule size and filling equipment.

Capsule Size Calculator: Manual Formula

Use this formula to estimate the capsule volume your formula needs:

Required Capsule Volume (ml) = Formula Weight (mg) ÷ Tapped Density (mg/ml)

Because 1 g/ml equals 1,000 mg/ml, you can also calculate it like this:

Required Capsule Volume (ml) = Formula Weight (mg) ÷ (Tapped Density in g/ml × 1,000)

Example

If your formula weighs 510 mg per capsule and the tapped density is 0.75 g/ml:

510 ÷ 750 = 0.68 ml

A required volume of 0.68 ml matches a Size 0 capsule. If your calculated volume is higher than 0.68 ml, you may need to upgrade to Size 00 or split the serving into two smaller capsules.

Quick Recommendation Table

Required Volume	Suggested Capsule Size
Up to 0.13 ml	Size 5
Up to 0.21 ml	Size 4
Up to 0.30 ml	Size 3
Up to 0.37 ml	Size 2
Up to 0.50 ml	Size 1
Up to 0.68 ml	Size 0
Up to 0.95 ml	Size 00
Up to 1.37 ml	Size 000

Need Help Choosing?

If you are not sure whether your formula should use Size 0, Size 00, or Size 000, send us your target dosage and powder density. Our formulation team can help estimate the most practical capsule size before you commit to bulk production.

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:

1. 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.
2. 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: If you are planning a market-ready product, our custom private label supplements service can help you compare capsule size, serving size, bottle count, and packaging options before launch. 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:

1. Bulk Density: The volume the powder takes up when it’s just sitting in a bag (lots of air).
2. 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 Measure Tapped Density Before Choosing a Capsule

Tapped density is the most useful number for capsule size selection because commercial capsule filling machines vibrate, tamp, or compress powder during filling.

A simple lab screening method is:

1. Weigh a known amount of your final blended powder.
2. Pour it into a graduated cylinder.
3. Record the initial bulk volume.
4. Tap or vibrate the cylinder until the powder volume stops decreasing significantly.
5. Record the final tapped volume.
6. Divide powder weight by tapped volume.

Tapped Density = Powder Weight ÷ Tapped Volume

Example

If 50 g of powder settles to 70 ml after tapping:

50 g ÷ 70 ml = 0.71 g/ml

If your target capsule fill weight is 500 mg:

500 mg ÷ 710 mg/ml = 0.70 ml

A required volume of 0.70 ml is slightly above Size 0 capacity, so you would likely need to consider Size 00, reduce the fill weight per capsule, improve powder density, or split the serving.

What Low Tapped Density Means

If your tapped density is below 0.50 g/ml, the formula is usually considered fluffy or bulky. This often happens with herbal leaf powders, fibers, mushroom powders, greens blends, and some plant extracts. In these cases, capsule count may increase unless the formulation is adjusted.

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.

Real B2B Formulation Example: When Size 0 Was Not Enough

A supplement brand planned to launch a botanical formula with a target fill weight of 500 mg per capsule. On paper, Size 0 looked acceptable because many capsule charts show Size 0 holding roughly 400–600 mg depending on density.

However, after testing the final blend, the tapped density was only 0.58 g/ml.

The required volume was:

500 mg ÷ 580 mg/ml = 0.86 ml

That meant the formula could not reliably fit into a Size 0 capsule. The brand had three practical options:

1. Move up to Size 00.
2. Split the serving into two smaller capsules.
3. Improve powder flow and density through formulation adjustments.

After comparing user experience and serving size, the brand selected Size 00 and adjusted the serving instructions to maintain compliance without overfilling the capsule.

This is why a capsule size chart should be used as a starting point, not the final production decision.

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 About Capsule Sizes

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

Torpac. Capsule Size Chart. Available at: https://www.torpac.com/Reference/Torpac%20Size%20Chart.pdf

Lightfoot, Donald K. Answers to 10 Common Questions About Capsule Filling. Tablets & Capsules / Capsugel. Available at: https://t2.capsugel.com/media/library/answers-to-10-common-questions-about-capsule-filling.pdf