Calculate Volume from Weight on Product with Varying Density

Hello! Hoping someone may be able to provide guidance.

We currently fill by weight and need to declare our net contents by volume (fl oz / ml). However, each production run will have varying density by +/- 0.05 g/cm^3. We sell the product frozen and instruct the consumers to use it melted. 

Does anyone have experience with something this? Is it common to adjust the fill weight for every production run? Or, should we use the max density (equating to the lowest weight) and be overfilling based on the declared contents? 

Thanks in advance! 

I use to make extracts and flavors.   We also used weight to check fill levels as it is much easier to in a production setting.   

We adjusted each run based off of the specific gravity of the batch.   

I guess you could the max density, but depending on the frequency of high density, cost of product and volume, you could have some less profitable runs do to shrink.