Inventor has several Design Calculators that perform a specific calculation without generating any geometry. The dialog box for calculators is also restricted to one tab, the Calculation tab. Calculators do generate a node in the assembly browser, which allows you to repeat the calculation with different input values. I'll cover the weld calculator in more detail than the others because all the calculators (weld, solder and hub joints, power screw, tolerance) are very similar.
There are a few interesting things to note about the weld calculator: