[Award Winner] Cartographical Economics and Demographics - A Guide to Realism

[atpollard]

So it's okay to have a planet a third the size of Earth, as long as it has about thrice Earth's density. (So for example a small planet with a very heavy core.)

Earth is already close to the density of iron (that large iron-nickel core), so a world with half the density of earth is far more likely than double the density of earth and you will quickly bump into a “depleted uranium core” upper limit on non-magical density.

2/ Gold pieces... in my opinion (as a student in economy) most fantasy writers do this wrong. Gold is extremely heavy, almost three times heavier than iron (the same volume), and therefore, it is highly
unrealistic to compare gold coins to modern day dollar in equivalence.

I agree … US$1 (or 1 Euro) should be closer to a traditional ‘copper piece’ with GP reserved for large transactions (like $100 bills).
(deflate the treasure hoards and costs)