By the way, when you intend to calculate the ratio of two elements, it is indispensable for you to confirm each size, first of all.
But, as you may easily notice, deciding a definite size of any element in the above line-ups is not possible.
It's because the sizes of all the elements are ranging within some extent.
For instance, the galactic diameter ranges from 10,000 to 100,000 light-years;
the Cosmic radius is estimated from 10 to 30 billion light-years;
and the cellular diameter ranges from 10 to 100 microns
Like this, every element has not a single value but is distributed within some range.
Nevertheless, in the material world, things are arranged in quite fair order.
When you carefully survey the magnitude extent of the members at each stage in the above line-ups, you may notice the fact that, in most cases, the upper value does not exceed 10 times of the lower value.
Now, my suggestion is that we calculate every ratio using mean values and admit a tenfold variation at every result.
Somebody may assert that comparing things of indefinite magnitudes is meaningless, but I think that it could be a quite fair method for dealing with the material world in which the sizes of elements of all stages are distributed within quite limited ranges.