This video shows the 100 largest empires in History.

Empires are defined as “any relatively large sovereign political entity whose components are not sovereign”

Data is mostly based on:
Rein Taagepera (1979). Size and Duration of Empires: GrowthDecline Curves, 600 B.C. to 600 A.D. Social Science History. Vol. 3, No. 3/4 (1979), pp. 115138
https://www.jstor.org/stable/1170959?...
https://en.wikipedia.org/wiki/List_of...

I updated Rein Taagepera‘s list because :
I drew the shapes of the countries on Google map and sometimes found different results from Taagepera's
I added some empires. For example, I added the United States in its XIXth century form, when it had a colonial empire consisting of the Philippines, Guam, Samoa, Puerto Rico, Cuba, Panama. I would not have classified the USA as an empire today.

You might notice that some empires look larger than others on the map, while being classified as smaller. That is because maps do not represent the actual size of a sphere like the earth.
Please check this video for more details :    • Why all world maps are wrong