What is your nation's size?

[Cyrenicae]

Adding up all the islands that make up our Federation, we are roughly the same size as the country of Ireland from earth.

[A Cornstar]

The entirety of USA, Canada, and Greenland

[The United Provinces of Leguria]

Not finalised, but at present, Leguria is a Portugal-sized island west of France and south of Ireland.

[Dushan]

The Dushan rule several celestial bodies of different shape and size and a number of artificial structures as well.

[Arpino]

I estimate Arpino nearly half of Canada's size, so at least 4mil km²

[Frisbeeteria]

Ducker has a territory of about 5192 (km²), just slightly larger than Trinidad and Tobago

[Matubuastan]

Matubua is almost exactly the size of Sweden, but is nowhere near as pleasant to be.

[Lemsrow]

Canonically, I’m a universal empire spanning 2 universes which contain 30 superclusters. And each supercluster is approximately 200,000,000 light years (or 200 million), and multiply all of the superclusters with it’s approximate size.

Equation

30
x 200,000,000
6,000,000,000

And here is where it gets complicated. Now we convert light years into square kilometers, I just looked at it. And it’s quite large to the point it has an e in the answer.

6,000,000,000 ly, converted into skm (square kilometer) is 4.953051e+54 square kilometers.

And let me remind you on already how massive a light year is. Here is how much square kilometers is required to be one whole light year.

1 ly, converted into skm is equals to 8.2555073e+44 square kilometers.

[Great Nortend]

A big larger than Austria.