How many mg is a size 1 capsule?

The amount of milligrams (mg) in a size 1 capsule can vary considerably depending on the type of medication or supplement it contains. Capsule sizes are not standardized, so manufacturers have some leeway in terms of the amount they can put in a particular capsule size.

Typical Range for Size 1 Capsules

That said, there are some general guidelines when it comes to the amount of powder that will fit into different capsule sizes:

  • Size 1 capsules: 50 to 300 mg
  • Size 2 capsules: 150 to 600 mg
  • Size 3 capsules: 300 to 1,000 mg
  • Size 4 capsules: 800 to 2,000 mg

So for a size 1 capsule, the typical range is about 50 to 300 mg of powdered contents. The actual amount for any given capsule depends on the density of the powder and how tightly it is packed into the capsule.

Factors Affecting Milligram Amount in Size 1 Capsules

There are a few key factors that affect how many milligrams a size 1 capsule can hold:

  • Density of the powder: How much space the powder takes up depends on how dense it is. A fine powder with small particles packs more tightly than a coarse powder. Dense powders like zinc oxide can hold more mg per capsule.
  • Padding agents: Some powders are bulked up with padding agents like microcrystalline cellulose that take up space without adding medicinal value. This decreases the mg of active ingredients.
  • Capsule fill percentage: Manufacturers don’t necessarily pack capsules as full as possible. Leaving some air space allows powders to flow freely. So fill percentage affects total mg.
  • Capsule shell weight: The weight of the empty gelatin capsule shell needs to be subtracted to determine the net weight of the contents.

Examples of Amounts for Specific Medications

Here are some examples of typical amounts of specific medications found in size 1 capsules:

Medication Typical mg per Capsule
Fluoxetine 20 mg
Vitamin B12 100 mcg (0.1 mg)
Fish oil 300 mg EPA/200 mg DHA
Turmeric 500 mg
Valerian root 250 mg
Magnesium 100 mg
Zinc 25 mg

As you can see, the amount of active medication in a size 1 capsule can range from tiny amounts like 0.1 mg up to 500 mg for common herbal supplements like turmeric. The powder density and composition helps determine the final mg per capsule.

Maximum Fill Weights

Capsule manufacturers provide guidelines on the maximum fill weights for each capsule size. However, these weights represent tightly packed, finely powdered ingredients and are not always achievable:

  • Size 1: 290-350 mg
  • Size 2: 450-560 mg
  • Size 3: 750-950 mg
  • Size 4: 1100-1300 mg

So while 350 mg is the maximum recommended fill weight for size 1 capsules, this would be for a very dense powder with optimal flow properties and 100% capsule fill. The actual achieved weight is often lower.

Strategies for Increasing Fill Weight

Manufacturers use various strategies to maximize fill weights if needed:

  • Use microencapsulated APIs that optimize powder flow.
  • Use a more concentrated extract.
  • Optimize excipient ratios to increase density.
  • Switch to a smaller capsule size – a 00 size holds about 20% more than a size 1.
  • Compress powders into a solid tablet rather than loose powder fill.

Equipment for Filling Capsules

There are two main types of equipment used to fill capsules with powders:

  • Manual capsule filling machines – These inexpensive machines allow users to fill around 24 capsules per minute. They are good for small batch production.
  • Automatic high-speed capsule fillers – Commercial machines can fill over 100,000 capsules per hour. They automatically measure precise amounts of powder and tamp the capsules for optimal fill weights.

The right filling equipment is important to achieve optimal precision and accuracy when encapsulating medicinal products or supplements.

Testing Fill Weights

Given the natural variability in achieving target fill weights, manufacturers will sample and test capsules from each batch to ensure they fall within the expected specifications:

  • Individual capsules are weighed to confirm their actual fill weight.
  • Sampled capsules are analyzed for potency to ensure proper dosage.
  • Minimum fill weight requirements are usually around 75% of maximum label claim.
  • Lot acceptance for potency varies depending on the type of drug or supplement.

By sampling and testing fill weights, manufacturers can confirm their production processes are adequately and consistently filling capsules to deliver the intended amounts of pharmaceutical or nutraceutical ingredients.

Regulations for Fill Weight Variability

Given the inherent variability in capsule filling, regulatory agencies allow for some leeway in fill weight variation while still requiring proper dosing:

  • United States Pharmacopeia (USP) allows up to +/-10% variability in fill weights relative to label claim.
  • In the EU, at least 2 out of every 6 capsules tested must be within +/-25% of average fill weight.
  • Health Canada allows up to 20% variability for nutritional supplements.

As long as sampled capsules meet these potency and weight standards on average, the batch can still be considered properly dosed and acceptable for release.

Troubleshooting Fill Weight Issues

Some potential causes and solutions for cases where fill weights are inconsistent or not meeting specifications:

Problem Potential Causes Solutions
Large fill weight variability
  • Powder flow issues
  • Inaccurate dispensing
  • Equipment issues
  • Improve powder flow properties
  • Recalibrate equipment
  • Evaluate equipment maintenance
Under-filled capsules
  • Low potency raw materials
  • Insufficient tamping
  • Update raw material specifications
  • Increase tamp force
Over-filled capsules
  • Excess powder in die
  • Reduced dosing precision
  • Adjust fill mechanisms
  • Recalibrate dosing

Troubleshooting and adjusting capsule filling processes helps ensure batches consistently meet fill weight and dosage targets.


The amount of milligrams in a size 1 capsule can vary considerably between 50-300 mg typically, and up to 350 mg maximum. The final fill weight depends on the powder properties, fill percentage, and precision of the encapsulation process. Manufacturers test fill weights to ensure capsules are dosed properly and meet pharmacopeia guidelines allowing for +/- 10-25% variability. By understanding and controlling these factors, capsule makers can produce accurately dosed capsules at the desired size 1 specifications.

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