by Guest » Wed Mar 30, 2005 8:04 pm
No general conversion is possible. You have to know the mass density of the material
As a point of reference, the density of water is 1 g/mL. Oils and alcohol are a little less, water with moderate amounts of salt, sugar, or other solid ingredients dissolved in it tend to be a little more.
For food products, the USDA has a pretty good database which collects data provided by manufacturers from the nutritional information labels on US foodstuffs sold to consumers.