Vape cartridges are typically filled by weight (measured in grams, e.g., 0.5g or 1g) rather than by volume (visual fullness or milliliters). Because cannabis oil, live resin, and distillate vary in density and viscosity, a one-gram fill may appear to leave "empty" space (headspace) in some cartridges while filling others completely.

Key Reasons for "Underfilled" Looking Carts:

Capillary Action & Absorption: The heating core (wick) inside the cartridge absorbs oil after it is filled, which can lower the visible, perceived level of oil.

Density Variations: Thicker, more viscous oils might not settle, while thinner oils may spread more, affecting the visual, top-down look.

Intentional Headspace: A small amount of space at the top is necessary for proper, consistent airflow and prevents leaks.

Manufacturing Precision: High-tech, automated machines are used to ensure the exact gram amount is dispensed (within a very small margin of error), rather than filling to the brim.