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Ulaanbaatar, 
Mongolia
1,596,556 people lived in Ulaanbaatar in 2025. It is the 308th largest of the world's 12,138 cities, and the largest in Mongolia, where it is the capital.
This is the UN's built-up area, drawn from satellite pictures and census maps rather than from the city limits, and the two can be a long way apart. The rule behind it.
Verified 2026-09-30 · 73 canaries
People · every five years · 1975 to 2050
How Ulaanbaatar grew
Count 10 people in Ulaanbaatar in 1975 and the same count gives 67.6 in 2025.
On the UN's projection it will have 2.1 million people in 2050. It passed a million people between 2010 and 2015.
projected (after 2025) · how sure the UN is: high moderate low
How to read this: one column every five years, 1975 to 2050; its height is the number of people. Hatched columns are the UN's projection. The thin strip beneath says how sure the UN is of each figure: the stronger the colour, the surer. A blank means the place was not on the UN's list of cities that year.
People · your family's years · 1975 to 2050
Ulaanbaatar through your family’s years
Put in the years your family were born. You’ll see how many people lived in Ulaanbaatar in each of those years, and when each of them turned 30.
Mongolia · every city · 2025
Where it is
How to read this: every dot is one of the 2 cities in Mongolia in 2025, and a dot's area is how many people live there. The ringed dot in colour is Ulaanbaatar; the grey dots are the rest. The outlines around them are neighbouring countries.
Area and built-up land · km²
How much land it covers
In 2025, Ulaanbaatar covered 241 km², and buildings, roads and other built-up land covered 66 km² of it. That is 41 m² of built-up land for each person, about a square 6 by 6 metres. Since 1975, its built-up land has grown to 3 times its size, and its people are 6.8 times as many.
How to read this: each pale square is the city's whole area, the strong square inside it the part that is built on; one scale for all three, so a bigger square is more land. Hatched is the UN's projection.
Of every 100 people in Mongolia
Its share of Mongolia
Of every 100 people in Mongolia in 2025, 45 lived in Ulaanbaatar, which is 1.6 million people.
How to read this: 100 squares, one for every 100th person in Mongolia; the coloured squares live in Ulaanbaatar. The grey rest live in other cities, in towns or in the countryside.
Ranked by people · 2025
Cities of a similar size
In the world, 2025
- 304 Budapest Hungary1,609,260
- 305 Warri Nigeria1,607,702
- 306 Tegucigalpa Honduras1,607,033
- 307 Maharajganj India1,601,258
- 308 Ulaanbaatar1,596,556
- 309 Havana Cuba1,593,580
- 310 Hargeisa Somalia1,593,542
- 311 Ta'izz Yemen1,586,739
- 312 Erbil Iraq1,582,829
How to read this: names are in order of size, the leading number being each city's rank among all 12,138 in 2025; the bars share a scale within a list. A jump in the ranks means a city under 300,000 people, which is not given a page here.
Apparatus
Sources and method
The figures for Ulaanbaatar are the UN's own, at five-year steps: an estimate for each of 1975 to 2025, then projection to 2050. Projected years are drawn hatched, and the UN publishes no range of uncertainty for a city. What a city means here, how the UN measures one, and why that number can differ from the one Ulaanbaatar publishes about itself: how the figures here are put together.
Sources: UN WUP 2025 · Natural Earth · flag-icons. Every source, its licence and how to cite it →
Verified 2026-09-30 · 73 canaries