Small rings in chemistry are usually laid out as polygons; 5-membered rings as a pentagon, 6-membered as a hexagon, and so on. Once you get beyond about 9-10, this tends to look a little nasty. Or at least, unconventional.

So for 'macrocycles', it makes sense to make a less circular, and more wavy outline. Or, to be more exact, there is an inner cycle and several outer cycles, like this:

To make it clearer, I have used a chemical-like structure with oxygens in the inner ring. These crown ethers are a particularly clear-cut case, as the ethylene linkages force the particular geometry of the drawing. However, it is not so obvious for other sizes of rings - what possible arrangements are there?

Well, it occurred to me today that there is a simple formula for these macrocycle drawings. For a ring of size

So for 'macrocycles', it makes sense to make a less circular, and more wavy outline. Or, to be more exact, there is an inner cycle and several outer cycles, like this:

To make it clearer, I have used a chemical-like structure with oxygens in the inner ring. These crown ethers are a particularly clear-cut case, as the ethylene linkages force the particular geometry of the drawing. However, it is not so obvious for other sizes of rings - what possible arrangements are there?

Well, it occurred to me today that there is a simple formula for these macrocycle drawings. For a ring of size

*n*with an inner ring of size*i*and outer rings or size*o*, you have to have*n = (i * o) - i*. The formula can be rearranged, but the idea is that you add up all the outer rings and …