Capsule Size and Fill Weight Calculator (Sizes 000 to 5)
The smallest capsule that holds the fill, the target fill weight and the machine output.
Try before you buy.
- Free preview: the method, the limits that apply and the verdict for your input; computed figures stay hidden until the pass.
- Locked until you unlock it: download and print.
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Report
Enter the dose and the formulation (or the fill weight) and the tapped density: the report appears here.
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Results are estimates from the formulas shown, not a professional design or certification. Have a qualified engineer verify anything safety-critical (structures, electrical installations, gas or pressure systems).
About the Capsule Size and Fill Weight Calculator (Sizes 000 to 5)
For a hard capsule product, the fill has to fit: the dose, the rest of the formulation and how densely the powder packs decide which capsule size it needs. This calculator works from the dose per capsule, the assay and any salt factor or overage, the share of the substance in the blend (or the other ingredients in mg) and the blend’s tapped density, and finds the smallest size from 000 to 5 whose volume holds the fill, with every size’s capacity at your density.
The report adds the target fill weight and its in-process range, the gross weight with the empty capsule, the limits of the harmonized uniformity of dosage units test that apply (mass variation or content uniformity, the largest fill-weight spread that still passes), and the filling machine’s output for the batch, with the blend you need. For compounding, it can make the fill up to the capsule’s capacity with a diluent. A list mode works out many products at once.
The free preview runs on your figures and shows the chosen size, the test that applies, the method and the limits; the figures, the PDF, the workbook and the printed fill weight record need a Premium pass. A professional calculation from published methods, not a prescription or advice for a person.
How to use it
- Under Work from, choose The dose (dose, assay, salt factor, overage and the blend’s composition) or The fill weight (a blend that is already formulated).
- Enter the tapped density of the fill in g/mL, measured by the harmonized bulk and tapped density method.
- Open Capsule chart to type your supplier’s volumes if they differ, and Weight limits, Filling machine and batch for the in-process limits, the empty capsule weight, the machine speed and the batch size.
- Read the verdict and the table of sizes. To make the fill up to the capsule’s capacity for hand filling, tick Fill the chosen size completely.
- With a Premium pass, download the report as PDF or XLSX or print it with the fill weight record; without one, the page shows the free preview with the figures hidden.
Examples
250 mg dose, assay 99.2 %, the substance 62.5 % of the blend, tapped density 0.72 g/mL
252.0 mg of substance, 403.2 mg of fill, 0.560 mL: size 0 (0.68 mL) is the smallest that holds it, 82 % full
Press Example on the page; it also fills in the limits, the empty capsule and a filling machine.
Size 0 (0.68 mL) with a blend of tapped density 0.80 g/mL
0.68 mL × 0.80 g/mL = 544 mg of fill at most
1,500 mg of fill at 0.80 g/mL
1.875 mL: more than size 000 (1.37 mL, 1,096 mg at this density); two size 000 capsules of 750 mg each
Common uses
- Formulators choosing a capsule size for a new strength or a new blend.
- Production planning a capsule batch: fill weight, limits, machine hours and blend.
- Compounding pharmacies making a dose up to the capsule’s capacity with a diluent.
- Checking which uniformity of dosage units test a capsule product needs.
- Comparing several products or strengths against one capsule chart.
How the size is chosen
- Substance per capsule = dose × conversion factor × (1 + overage) ÷ assay. The conversion factor is the weighed form over the label-claim form, for example a salt’s molar mass over the base’s; use 1 when the dose is the substance you weigh.
- Fill weight = substance ÷ its share of the fill, or substance + the other ingredients in mg.
- Fill volume (mL) = fill weight (g) ÷ tapped density (g/mL).
- A size holds the fill when the fill volume is at most its volume (times the share of the volume you choose to use, 100 % by default). The smallest such size is chosen; each size’s capacity at your density is volume × density.
The default chart is a capsule supplier’s published volumes (size chart): 000 1.37 mL, 00 0.90, 0 0.68, 1 0.48, 2 0.36, 3 0.27, 4 0.20 and 5 0.13 mL. Volumes differ a little from maker to maker and between capsule types, so type your own supplier’s values when they differ, and add elongated sizes such as 00el or 0el.
Tapped density
The calculator needs the blend’s tapped density, measured by the harmonized method of the Japanese, European and United States pharmacopoeias (JP General Tests 3.01, interchangeable under ICH Q4B): about 100 g of powder in a 250 mL cylinder with an untapped volume of 150 to 250 mL, read after 10, 500 and 1,250 taps; when the 500- and 1,250-tap volumes differ by 2 mL or less, the 1,250-tap volume is the tapped volume, and tapped density = mass ÷ tapped volume.
A filling machine that compresses the powder into a plug (a dosator or tamping pins) can put more mass into a capsule than the tapped density suggests, and hand filling can put less. Use the result to choose the size, then confirm the fill weight with trial capsules.
Uniformity of dosage units
The harmonized chapter (JP 6.02, with Ph. Eur. 2.9.40 and USP <905>) allows mass variation for hard capsules holding 25 mg or more of a drug substance that is 25 % or more of the contents; otherwise content uniformity (individual assays) is required.
In mass variation each capsule’s content is estimated from its net fill weight: x = w × A ÷ mean w, where A is the batch assay. The acceptance value of the first 10 capsules, AV = |M − mean| + 2.4 s, must not exceed L1 = 15.0, with M equal to the mean between 98.5 and 101.5 % and the nearer bound outside it. If it does, 20 more are tested: the AV of all 30 (k = 2.0) must not exceed L1, and no capsule may fall outside 75–125 % of M (L2 = 25.0). With the batch at 100 % of the label claim, AV = 2.4 × RSD, so the fill weights’ relative standard deviation may be at most 6.25 % to pass with the first 10. The report works this out for the batch assay you enter.
Fill weight limits and the machine
- In-process limits are your own, from the batch record or procedure: the report applies the single and mean fill weight limits you enter, and adds the empty capsule weight for gross weights.
- Machine output = rated speed × running efficiency (capsules per hour). With the batch size, the report gives the filling time and the blend needed: blend = fill weight × capsules ÷ (1 − the share of the blend lost in the process).
- Compounding: with “Fill the chosen size completely”, the fill weight becomes the size’s capacity at your density and the rest of the capsule is diluent: diluent = capacity − substance. This assumes the diluent packs like the blend; check the density of the final mixture.
Limitations
- A professional calculation from published methods, not a diagnosis, a prescription or advice for a person; formulation decisions stay with qualified staff.
- The tapped density and the chart volumes are estimates of how a powder fills a capsule; machines and hand filling differ, so confirm the size and the fill weight with trial capsules.
- Capsule volumes are a supplier’s published values: use your own supplier’s chart for the final choice.
- The uniformity limits are those of the harmonized test; a monograph or a marketing authorisation may set others.
- Inputs stay on this page until you reload it, except the capsule chart you edit, which this browser remembers; nothing is uploaded.
Privacy
On this device; its files download once
Everything is worked out in your browser: the doses, densities and batch figures you type are never uploaded or stored. Only the capsule chart you edit is remembered in this browser’s storage for your next visit; “Default chart” clears it.
Frequently asked questions
What do I get without a pass?
Without a pass, Capsule Size and Fill Weight Calculator (Sizes 000 to 5) shows the method, the limits that apply and the verdict for your input; computed figures stay hidden until the pass. Until you unlock it, the result can’t be downloaded or printed. A Premium or Ultimate pass, a one-time payment that never renews, unlocks the full result. The pricing page lists the passes and their prices.
What capsule size do I need for 500 mg?
It depends on the density of the fill, not only on the milligrams. At a tapped density of 0.8 g/mL, 500 mg is 0.625 mL: size 0 (0.68 mL) holds it. At 0.6 g/mL it is 0.833 mL and needs size 00 (0.90 mL). Enter the dose, the composition and the density to see every size.
Why tapped density and not bulk density?
A capsule is filled with a packed powder, and capsule charts give capacity as volume × density. Tapped density, measured by the harmonized method, is a reproducible measure of packed powder; the bulk (untapped) density would choose a size that is larger than needed.
What is the conversion factor?
The mass of the form you weigh per mass of the form the dose is labelled as: for a dose labelled as the base and weighed as a salt, the salt’s molar mass divided by the base’s. Use 1 when the dose is the substance you weigh.
Which uniformity test applies to my capsules?
Under the harmonized chapter, mass variation may be used for hard capsules with 25 mg or more of a drug substance making up 25 % or more of the contents; otherwise content uniformity is required. The report states which applies to your dose and fill weight.
How is the machine output worked out?
Capsules per hour = the machine’s rated speed × the running efficiency you enter (100 % is the rated speed without stops). The filling time is the batch size divided by that output. The blend needed is the fill weight × the capsules ÷ (1 − the share of the blend lost in the process): with 1.5 % lost, 100 kg of blend in the capsules needs 100 ÷ 0.985 = 101.52 kg charged.