A standard fill is when you fill the container up to its designated fill capacity. If a bottle is sold as a 4 oz or 120ml bottle, the fill line is designated by using water, the world-wide universal ingredient. You should always determine your best “cosmetic” fill for your product and the product’s own viscosity. Then use this fill capacity in your label claim.
The overflow capacity of a container is the total amount of product which can be placed into the container until it reaches the overflow point. This information is handy to know if your product has a tendency to expand, possibly leak, or requires more head space (air space) above the product.
It’s a good idea to test your product in your preferred container with the preferred closure.