Understanding Empty Capsule Sizes
It is not uncommon to have questions or to be unclear about the how the sizing of empty capsules works. Because the larger sizes are labeled with higher numbers, the sizing method can seem counterintuitive. For example, a # 5 capsule is smaller than a #1 capsule. A “000” (triple zero) capsule is the largest size available. In cases where capsule sizes are indicated with "0" names, 000s are the largest, while 0s are smaller.
Understanding sizing of capsules is the first step in determining what you will need for your application. The density of the powder formulation you will be using and the intended dosage are the factors that will determine the capsule size that you need.
When you have determined the needed dosage, you can either try to consolidate multiple dosages into a larger capsule such as the 000 (ideal for adults and large pets such as dogs and horses) or divide the dosage among several smaller capsules such as 0s and 1s. Because these smaller capsule sizes are easier to swallow they are most suitable for children and smaller pets.