Need to know what size tubing fits inside another. Is there a chart or something that lists this?

For example if I want to build some adjustable table legs out of 2/2 square what smaller tubing would I need that would slide nicely into the 2x2?.

Same questions works for round, rectangle, even channel I would think. Would want "closest fit" and not 1x1 inside 2x2.

Would be nice to have achart or list or calculator or .... to make choices for orders.