How to Choose the Right Capsule Size for Your Formula

Choosing the right capsule size decides how many capsules make up a dose, how fast your line runs and how easy the product is to swallow. The method is simple: work out the volume your dose needs, then pick the smallest standard size that holds it.

Step 1: Know your fill weight and powder density

You need two numbers:

• Fill weight per capsule: the dose of the blend, including excipients, in milligrams.
• Tapped density of the finished blend, in grams per millilitre (g/mL). Use tapped rather than bulk density, because tamping and dosing compress the powder. Most supplement powders fall roughly between 0.4 and 1.0 g/mL.

Step 2: Calculate the volume you need

Volume (mL) = fill weight (g) ÷ tapped density (g/mL)

Example: a 500 mg dose of a blend with a tapped density of 0.6 g/mL needs 0.5 ÷ 0.6 ≈ 0.83 mL.

Step 3: Pick the smallest size that fits

Size	Typical volume (mL)	Fill at 0.6 g/mL (mg)	Fill at 0.8 g/mL (mg)
000	1.37	822	1,096
00	0.91	546	728
0	0.68	408	544
1	0.50	300	400
2	0.37	222	296
3	0.30	180	240
4	0.21	126	168

In the example, 0.83 mL fits in a size 00 capsule (0.91 mL) but not a size 0 (0.68 mL). Full dimensions and fill weights at more densities are in our capsule size chart.

Step 4: Check the practical limits

• Leave headroom. Real fill weights depend on flow, compaction and the dosing method. A capsule filled close to its theoretical limit can be hard to close consistently, so confirm with a pilot run on your own machine.
• Swallowability. Sizes 0 and 00 are the most common for adult supplements. Size 000 suits high-dose products but is large; splitting the dose into two smaller capsules can be friendlier for consumers.
• Change parts. Each size needs its own change parts on most encapsulators. Standardising on one or two sizes across your range reduces changeover time and tooling cost.
• Too much space. If your dose only half-fills a capsule, a smaller size or a denser blend usually gives a more consistent fill weight.

Step 5: Choose material and colour

Once the size is fixed, choose the shell material (see gelatin vs HPMC), any enteric release, and the cap and body colours. Two-tone colours help production staff and consumers tell products apart.

Ready to order?

Send us the size, material, colour and approximate quantity through our bulk quote form. If you are between two sizes, include your fill weight and tapped density and we will help you decide.