The Largest Empires in History, Compared at True Size

By area, the British Empire was the largest in history: about 35.5 million km² around 1920, by common published estimates. The Mongol Empire was the largest contiguous empire, about 27.1 million km² in 1279 as measured from its outline in TrueSize. The Russian Empire and the Soviet Union each covered about 22 million km².

The Mongol Empire (1279), the Russian Empire (1895) and the Qing dynasty (1759) side by side on the equator, each at its true size.

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The numbers

Empire	Year	Area
British Empire	1920	about 35.5 million km² (published estimate)
Mongol Empire	1279	27.09 million km² (measured in TrueSize)
Soviet Union	1945 to 1990	22.02 million km² (measured in TrueSize)
Russian Empire	1865	21.97 million km² (measured in TrueSize)
Spanish Empire	1815	13.94 million km² (measured in TrueSize)
Qing dynasty	1759	12.58 million km² (measured in TrueSize)
Roman Empire	116 AD	4.83 million km² (measured in TrueSize)

For scale: the entire land surface of Earth is about 148.9 million km². At about 35.5 million km², the British Empire at its largest covered almost a quarter of it, and the Soviet Union covered about 15%.

Why the figures differ

Empires are hard to measure. Historians count colonies, protectorates and spheres of influence differently, and some borders were never fixed. A sea route is not territory, and a claim over a desert may be only on paper. The TrueSize figures use one outline per snapshot year, so the same method applies to every empire and you can compare them fairly. Other sources can give different numbers, often within a few million km².

Two empires deserve a note. The British Empire was spread across every continent, so it never formed one block on the map; its outline in TrueSize measures 33.6 million km² in 1920 (see it year by year). The Mongol Empire is the largest contiguous land empire, a single block across Eurasia.

Try it yourself

1. On the Home tab, click the Modern/Historical switch to open the timeline.
2. Use Go to year to set 1279 and search for the Mongol Empire, then pin it so it keeps its year. Repeat with 1895 and the Russian Empire, and with 1759 and the Qing dynasty.
3. Drag them to the equator next to each other. The Stats button on the Tools tab shows the combined area.

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More comparisons

• How big was the British Empire?
• The Mongol Empire at true size
• How big was the Roman Empire?
• Soviet Union vs USA
• Historical Borders Map: See Any Country's Borders by Year

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