With these calculators you can calculate Anglo-American units to the standards units (SI-units). This may be useful, because most American and British use American or British units and European use the standard metric units. With the conversion calculators you can convert the units that are most commonly used. There is a small overview of the units that are mostly used in the industry in the process flow calculator. The other conversion programs have more units to convert and they have some useful back ground information. You can also calculate the money you can save when you re-use rainwater that falls instead of tap-water (precipitation calculator) and the energy cost when you use a boiler to heat water (energy cost).