Empty Capsules 101: Choosing the Right Size and Type

Choosing an empty capsule seems simple until you are staring at eight sizes and four shell materials. This guide breaks down the two decisions that matter: size and type.

Capsule sizes and fill volume

Capsule sizes run from the largest, 000 (~1.37 ml), down to the smallest, 5 (~0.13 ml). The most common supplement sizes are 00 and 0. Your ideal size depends on your powder's density and the target dose per capsule — denser powders pack more milligrams into the same volume.

Shell types compared

• Gelatin — economical, clear, fast-dissolving; the classic choice.
• HPMC (vegetarian) — plant-based, low moisture, halal/kosher friendly; ideal for probiotics and hygroscopic blends.
• Pullulan — natural, premium, excellent oxygen barrier for sensitive actives.
• Enteric / DR — resists stomach acid to protect and target-release actives.

Matching capsule to formula

For a plant-based brand, HPMC or pullulan align with your positioning. For oxygen-sensitive actives such as probiotics or oils, pullulan's barrier properties help. For acid-sensitive enzymes, enteric shells are worth the premium.

Quality checklist

Consistent wall thickness, reliable dissolution, low moisture, and certifications (non-GMO, halal, kosher) all signal a capsule that will run cleanly on your filling equipment. Celfiu stocks every size and type so you can match capsule to formula without compromise.