"The material presented here is a community original creation, intended for use with the GURPS system from Steve Jackson Games. This material is not official and is not endorsed by Steve Jackson Games."
Realm Size Value is a Realm Management value determined by roughly how much area the realm occupies, in square miles. Note that a realm's raw size only allows you to add more things to an empty realm--owning the entire Antarctic doesn't mean much if no one lives there--or no one can!
The formula is (ln(2*Area) / ln(10)) * 3 = Size as Area = e^(ln(10)*Size/3)/2[1] This simplifies to log(2*Area)*3 = Size[2]
This table lists the actual size values as notes. As with Size one goes with the closest integer.[3]
↑Actual size value is ~13.562. This is for the country not the Danish Realm which includes Greenland kicking it up to 2,220,072 mi² or +19.942 which rounds to +20