Capsule sizes are systematically numbered from largest to smallest, with size 000 being the largest and size 5 the smallest. The size of a capsule directly correlates with its volume and weight capacity. For instance, size 000 capsules have a volume of approximately 1.37 ml and can hold up to 1370 mg, whereas size 5 capsules have a volume of 0.13 ml and a capacity ranging from 100 to 150 mg. The exact weight capacity is influenced by the density of the powder being encapsulated. Below is a detailed table outlining the various capsule sizes, their approximate volumes, weight capacities, and common uses:
| Capsule Size | Approximate Volume (ml) | Approximate Weight Capacity (mg) | Common Use |
| 000 | 1.37 | 950 - 1370 | High dosage supplements |
| 00 | 0.95 | 665 - 950 | General purpose for supplements |
| 0 | 0.68 | 475 - 665 | Smaller dosages, easy-to-swallow option |
| 1 | 0.50 | 350 - 475 | Lower dosage supplements |
| 2 | 0.37 | 250 - 350 | Moderate dosage |
| 3 | 0.30 | 200 - 300 | Small dosage |
| 4 | 0.21 | 150 - 200 | Very small dosage |
| 5 | 0.13 | 100 - 150 | Microdosing, children, or smaller animals |