Capsule sizes run from 000, the largest standard size, down to 5, the smallest. For dietary supplements, sizes 00, 0, 1 and 2 cover most formulas. The right one for your product depends on how much powder you need per serving, how dense that powder is, and how easy you want the capsule to swallow.
This guide gives you a capsule size chart with volume, fill capacity and dimensions for sizes 000 to 4, then walks through how to choose a size for your formula.
Quick answer: how much fits in each size?
- Size 00: 0.91 mL, about 550 to 910 mg of powder
- Size 0: 0.68 mL, about 410 to 680 mg
- Size 1: 0.50 mL, about 300 to 500 mg
- Size 2: 0.37 mL, about 220 to 370 mg
Ranges assume a powder density of 0.6 to 1.0 g/mL. Lighter powders fill toward the low end; denser powders toward the high end.
Standard capsule sizes, shown in proportion.
Capsule size chart
The figures below are typical published values for standard two-piece gelatin capsules. Vegetarian (HPMC) capsules and different capsule suppliers vary slightly. For example, one major supplier lists its vegetarian size 00 at 0.95 mL instead of 0.91 mL.
| Size | Volume (mL) | Fill at 0.6 g/mL | Fill at 0.8 g/mL | Fill at 1.0 g/mL | Closed length | Diameter |
|---|---|---|---|---|---|---|
| 000 | 1.37 | 822 mg | 1,096 mg | 1,370 mg | 26.1 mm | 9.9 mm |
| 00 Nutrafill fills | 0.91 | 546 mg | 728 mg | 910 mg | 23.3 mm | 8.5 mm |
| 0 Nutrafill fills | 0.68 | 408 mg | 544 mg | 680 mg | 21.7 mm | 7.6 mm |
| 1 Nutrafill fills | 0.50 | 300 mg | 400 mg | 500 mg | 19.4 mm | 6.9 mm |
| 2 Nutrafill fills | 0.37 | 222 mg | 296 mg | 370 mg | 18.0 mm | 6.4 mm |
| 3 | 0.30 | 180 mg | 240 mg | 300 mg | 15.9 mm | 5.8 mm |
| 4 | 0.21 | 126 mg | 168 mg | 210 mg | 14.3 mm | 5.3 mm |
Source: published size specifications from Capsugel (Lonza) for its Coni-Snap gelatin capsules. Dimensions are overall closed length and external diameter of the cap, rounded.
00 vs 0 vs 1 vs 2: what’s the difference?
Size 00
The largest of the common supplement sizes, at 23.3 mm long and 0.91 mL. It’s the go-to choice when you need to fit a larger dose into fewer capsules. Some customers find it harder to swallow, so it suits adult products where fewer capsules per serving matters more.
Size 0
A balance between capacity and ease of swallowing, at 21.7 mm and 0.68 mL. Size 0 holds about 75% as much as size 00 and works for a wide range of formulas.
Size 1
Noticeably smaller, at 19.4 mm and 0.50 mL. A good fit for lower-dose formulas and for customers who prefer smaller capsules.
Size 2
The smallest of the four, at 18.0 mm and 0.37 mL. Best for potent ingredients with small doses, or for products where easy swallowing is a priority.
How much powder fits? It depends on density
A capsule size has a fixed volume, but how many milligrams that volume holds depends on your powder’s density. A quick way to estimate it:
Fill weight (mg) ≈ capsule volume (mL) × powder density (g/mL) × 1,000
Example: a size 0 capsule (0.68 mL) filled with a powder at 0.8 g/mL holds about 0.68 × 0.8 × 1,000 = 544 mg.
Light, fluffy powders, such as many botanical extracts, sit at the low end of the range. Dense powders, such as many minerals, sit at the high end. Your manufacturer can measure your blend’s density and confirm the real fill weight before production.
How to choose a capsule size for your supplement
- Add up your fill weight per serving. Total every ingredient in the serving, including any excipients like flow agents.
- Estimate your powder density. If you don’t know it, use 0.8 g/mL as a starting point, then confirm with your manufacturer.
- Work out capsules per serving. Divide your fill weight by each size’s capacity, then round up. For example, a 1,500 mg serving at 0.8 g/mL doesn’t fit in two size 00 capsules (2 × 728 = 1,456 mg), but it does fit in three size 0 capsules (3 × 544 = 1,632 mg).
- Think about your customer. Fewer, larger capsules or more, smaller ones? Older customers and children often prefer smaller sizes.
- Check your bottle. More capsules per serving means more capsules per bottle, which affects bottle size, packaging cost and price per serving.
Gelatin vs vegetarian capsules
Both gelatin and vegetarian (HPMC) capsules come in the same standard sizes, with small differences in weight and capacity. Vegetarian capsules suit vegan and vegetarian products and customers who avoid animal-derived ingredients. Ask about shell options when you request a quote.
Outgrowing hand-filling?
If you’re filling capsules by hand or on a small machine, there’s a point where your time is better spent selling than filling. Nutrafill fills sizes 00, 0, 1 and 2 on automatic encapsulation equipment, with counting and bottling, 500-unit minimums and third-party microbial and strength testing on every finished product. Learn about our capsule manufacturing.
Frequently asked questions
Which is bigger, a 0 or a 00 capsule?
Size 00 is bigger. It holds about 0.91 mL, compared with 0.68 mL for size 0, and it’s about 1.6 mm longer.
How many mg fit in a 00 capsule?
About 550 to 910 mg, depending on powder density. At a typical density of 0.8 g/mL, a size 00 capsule holds about 730 mg.
What is the largest capsule size?
Size 000 is the largest standard size, at about 1.37 mL. It’s less common in supplements because it’s harder to swallow.
What is the most common capsule size for supplements?
Sizes 00 and 0 are widely used for supplements because they balance capacity with ease of swallowing. Sizes 1 and 2 are common for lower-dose formulas.
What capsule sizes does Nutrafill fill?
Sizes 00, 0, 1 and 2, with our runs most efficient at around 300,000 capsules and minimums starting at 500 units.
Need help choosing a size?
Send us your formula and target dose, and we’ll recommend a capsule size and put together a quote. Minimums start at 500 units.