Private Label Capsule Manufacturing: Sizes, Fill Weight and Shell Choices

The capsule is a precision dosing device, not a commodity

Capsules are the default format in private label supplements for good reasons: they need no compression science, they mask taste, they suit vegan and allergen positioning, and the dose can be changed without reformulating the shell. Because the format feels commodity, many brand owners hand a brief to a factory and treat everything between the shell walls as the factory's problem. That is exactly how projects end up with a capsule that cannot hold the claimed dose, a shell that turns brittle in a humid warehouse, or a fill that is 40 percent inexpensive excipient.

In private label capsule manufacturing, a two-piece capsule is a volumetric metering device. The shell fixes the volume, the blend's density fixes how much mass fits in that volume, and the machine fixes how repeatable that mass is from capsule to capsule. Three numbers - shell size, tapped density of the blend and shell moisture - decide most of the outcome, and none of them appear on the label.

We produce hard capsules across the full capsule product range - single-ingredient actives, mineral complexes, mushroom extracts and multi-strain probiotics - alongside the wider supplement catalogue. This guide covers the decisions that run through every one of those SKUs; if you are still choosing between formats, start with our dosage form comparison and come back here once the capsule has won.

Capsule size is a volume decision, not a branding decision

Hard capsule sizes run from 000 down to 5, and the numbering runs backwards: the bigger the number, the smaller the capsule. A size 000 holds about 1.37 mL, a size 0 about 0.68 mL, a size 3 about 0.30 mL and a size 5 only 0.13 mL. Which size you land on is not a design flourish - it is the intersection of the dose your formula needs, the density your blend can actually reach, and what a consumer will swallow twice a day without complaint.

Two practical filters sit on top of the table. First, swallowability: sizes 000 and 00 are hard for older consumers and impossible for children's lines, so most daily-use supplements settle on size 0 or smaller even when a larger shell would simplify the dose. Second, machine reality: the encapsulation machine must hold the filled capsule within a tight weight band at thousands of capsules per hour, and very light or very dense blends both push a size toward its limits. When a brand asks for 1,000 mg of active in one capsule, we check whether that is a size 000 problem or a two-capsule problem before anything else.

Fill weight comes from tapped density, not from your brief

The most common briefing error in private label capsule manufacturing is stating a per-capsule milligram target without stating the blend's density. Powder in a bag sits at its bulk density; after tapping, vibration and machine compaction it settles at its tapped density, which can be 20 to 40 percent higher. Fill weight is a function of shell volume and tapped density, not of the number on the brief. A fluffy botanical powder at 0.4 g/mL tapped density cannot reach 500 mg in a size 0 no matter how the machine is tuned - the blend either gets densified through granulation or spray-dried raw material, the dose gets split across two capsules, or the shell gets bigger. Each of those levers moves cost somewhere else.

The spread across real formulas is wider than most buyers expect. From our own capsule catalogue, the same nominal 'capsule' carries anything from 200 mg of standardized extract to over 1,100 mg of a dense mineral blend:

Read that chart as a density story, not a potency story. Creatine and HMB fill heavy because the raw material crystallizes dense; standardized botanical extracts fill light because they are spray-dried onto carriers and sit at 0.35 to 0.55 g/mL. When a competitor's capsule claims the same dose in fewer capsules, the difference is usually blend density and capsule size - not a better raw material.

Our densest catalogue formulas show both ends of the lever: HMB at 1,000 mg per capsule leans on a dense crystalline raw material, while NAD+ and trans-resveratrol at 750 mg per capsule spreads 1,500 mg of active across two vegetable capsules to stay inside a swallowable shell.

Shell material: gelatin versus HPMC

The shell is roughly 20 to 30 percent of the capsule's total weight and a much larger share of its failure modes. Bovine gelatin remains the default: it runs on every encapsulation machine, costs less and dissolves fast. Hypromellose (HPMC) vegetable shells cost more but hold less water - about 4 to 6 percent shell moisture versus 13 to 16 percent for gelatin - which matters more than any marketing difference.

The row that saves the most money is the one nobody asks about. Gelatin is chemically reactive: aldehydes and reducing sugars in some botanical extracts and flavors cross-link with the shell protein during storage, forming an insoluble pellicle that slows dissolution. The capsule can pass every test at release and fail its six-month accelerated stability dissolution - which means the batch is reworked or scrapped months after the money was spent. If your formula contains certain plant extracts, ask which shell the stability data was generated on. Moving to HPMC, adjusting the fill system or adding a protective excipient are all cheaper than a failed stability study.

Excipients are the invisible half of the fill weight

A 500 mg capsule is rarely 500 mg of active. Microcrystalline cellulose carries volume, colloidal silicon dioxide keeps the blend flowing, and magnesium stearate keeps it from sticking to the machine - typically 0.5 to 1 percent of the fill. This is normal and honest formulation. What separates a good capsule from a lazy one is whether the excipient system was designed around the active's flow behavior or copied from the last job.

The inside-the-industry detail is blend time. Magnesium stearate is a lubricant, and lubricants work by coating every other particle. Blend a powder with magnesium stearate for more than about 5 to 10 minutes, or push it above roughly 1 percent, and you over-lubricate: the blend flows beautifully on the machine and disintegration slows on the finished dose, because the same hydrophobic film that helps the machine keeps water out. Production practice is to add the glidant first, blend, then add the lubricant last and blend as briefly as the process allows. A buyer never sees this parameter, but it shows up in the dissolution result.

Granulation is the usual fix, and it is worth understanding what you are buying. A wet or dry granulation step densifies the blend before it reaches the filling machine, converting a fluffy 0.4 g/mL powder into a free-flowing granule that meters precisely and packs predictably. The costs are a drying stage, a mill screen, a density check on the granule and typically a few days of schedule - modest, and far cheaper than discovering at filling that your hero dose does not fit the shell you already printed artwork for. Co-processed and spray-dried grades of some actives reach the same result with no extra step at all, at a higher raw material price.

Particle size behaves the same way from the other end. Very fine milled powders - anything much below roughly 100 mesh - aerate and flood in the dosing disc, which shows up as capsule-to-capsule weight variation. Coarser granulations flow predictably but pack less mass per shell. The working target is a blend with a Carr index comfortably under about 20 percent; if the raw material cannot get there, the fix is a granulation step or a co-processed grade, and both are quoted as line items.

Count per bottle is a cost decision disguised as a packaging decision

Bottle counts of 60, 90 and 120 look like marketing choices, and they are - but they are also cost multipliers that interact with capsule size. A bottle that holds 120 size 0 units may hold only 90 size 00 units, which can force a bigger, more expensive bottle per unit, more desiccant, more filler and more freight volume per dose delivered. The count also sets the production arithmetic: at our standard minimum of 500 units, a 120-count bottle is 60,000 filled capsules and a 30-count bottle is 15,000 - same setup work on the line, spread across very different volumes.

Freight closes the loop. Supplement bottles ship by volume, not by weight, so a bottle chosen one size up for the same count adds a double-digit share to per-unit landed cost once pallets are calculated. Desiccant, cotton or a molded tray add pennies per bottle and protect months of shelf life in humid destinations, which makes them a first-quotation item rather than an afterthought once a container arrives with soft shells.

The practical sequence we run with brand partners: fix the daily dose and serving size first, derive the capsule size from the blend's tapped density, choose the count from the positioning (daily, monthly or value format), and only then cost the bottle. Running it backwards - falling in love with a 30 mL bottle and then discovering the capsule count does not fit - is a small delay repeated on half the first projects we see.

What a real capsule release specification contains

Capsules are the easiest dosage form to test, which is why thin release documents are a red flag. In private label capsule manufacturing the release specification is effectively the contract: everything you will later wish you had asked for either lives there or does not exist. A finished batch of hard capsules should be released against a specification that reads like this:

Ask to see a completed lot's certificate against this shape, not a one-page pass certificate. The difference between a document that names methods, limits and results and one that prints a row of check marks is the difference between a factory and a trading company.

How those documents fit into market access - FDA structure-function rules, cGMP expectations and Halal certification - is covered in our guide to global supplement regulations. For capsules the Halal question lands on the shell: a bovine gelatin shell needs certified Halal slaughter documentation, while an HPMC shell sidesteps the question entirely.

MOQ, lead times and a realistic capsule schedule

Our standard minimum for private label capsule manufacturing is 500 units per product, and on an established format with stock packaging a production run completes in about 15 days, with expedited processing down to 10 days. The schedule stretches for two reasons that are specific to capsules: a custom shell color or two-tone shell adds shell production and minimum-quantity constraints at the shell supplier, and a blend that needs granulation adds a processing step before encapsulation even starts.

Expedited runs compress the production window by overlapping steps that would otherwise queue - shell receipt, blending, filling, polishing and packaging inspection - and they work because filling a validated formula is a short, well-understood operation. What an expedite fee cannot compress is the shell supplier calendar for a custom color or the granulation queue for a dense blend, which is why the checklist at the end of this guide asks you to settle both before the purchase order.

The full arithmetic - how artwork, bottle choices and count move both the minimum and the calendar - is set out in our guide to MOQ and lead times in supplement manufacturing. The short version for capsules: the shell is ordered before your artwork is approved, so lock the shell decision early. If speed to market is the deciding factor, our hard capsule fast-track guide sets out the order timeline, what a no-sample round actually means and the five things that delay a capsule project.

A pre-brief checklist for a capsule project

• State the daily dose and serving size before discussing capsule size, shell or count.
• Ask for the blend's tapped density, not just the ingredient list - it is the number that decides what fits in a shell.
• Check whether the target fill weight lands in a swallowable size 0 or 1; if it needs a 000, ask whether two smaller capsules serve consumers better.
• Decide gelatin versus HPMC from the fill's hygroscopicity and your positioning, not from a price list alone.
• If the formula contains botanical extracts, ask whether the stability data was generated on the same shell chemistry you are buying.
• Request the lubricant level and blend time in the process description; over-lubrication shows up as slow dissolution months later.
• Confirm the release specification covers disintegration, fill weight variation, shell moisture, microbiology and per-active identity.
• Fix the count per bottle together with capsule size and bottle volume, then cost the packaging once, not three times.
• If a Halal or vegan claim applies, settle the shell before the formula is frozen - it changes the shell supplier and the documentation.
• Lock the shell color early: custom shells carry their own minimums and lead times ahead of the production run.