Feature suggestion: cross-metric conversions

[zszabo2000]

By "cross-metric" i simply mean converting from e.g. mass to volume. Naturally, this is only meaningful for certain substances and under certain conditions. I am mainly thinking liquid water (or milk, or cooking oil) at standard temperature and pressure, although additional flexibility can be added by allowing to specify min/max density values as optional settings (if this functionality is provided, the min-max values should be preset and resettable to sensible values).

Purpose: Cooking recipes frequently state ingredient quantities in terms of volume, while professionals always measure by weight. Additionally, someone might have only measuring cups, but no mass scale (or vice versa). Most such ingredients (eg water, an incompressible fluid in liquid state) can be easily converted from volume (eg liters or cups) to mass (grams or lbs), because they're assumed to be under room temperature conditions (1 atmosphere, ~20°C / 72°F). For things like flour that are compressible, there are standard densities available (eg on FDA nutrition info label: 120g/cup ~= 0.507 g/cm^3).

Optional: Additional flexibility can be added by allowing to specify min-max values (eg a typical bag of flour weighs 4.98-lbs, which is 2258.5g, and fits into a ~22x14x10 cm^3 =3080 cc paper bag, meaning it is much more compact compared to the FDA label, at 0.733g/cc density).