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Nairobi, 
Kenya
6,134,334 people lived in Nairobi in 2025. It is the 65th largest of the world's 12,138 cities, and the largest in Kenya, where it is the capital.
That figure counts the whole built-up area, not the area Nairobi governs, so it may be far from the number the city publishes about itself. How the UN measures a city.
Verified 2026-09-30 · 73 canaries
People · every five years · 1975 to 2050
How Nairobi grew
Count 10 people in Nairobi in 1975 and the same count gives 114 in 2025.
On the UN's projection it will have 8.5 million people in 2050. It passed five million people between 2015 and 2020.
projected (after 2025) · how sure the UN is: high moderate low
How to read this: each column is one of the UN's five-yearly estimates, 1975 through 2050, and taller means more people. Where a column is hatched the year has not happened yet. The strip under the columns is the UN's own confidence in each figure, palest where it is least sure; where it is blank the city was not on the list at all.
People · your family's years · 1975 to 2050
Nairobi through your family’s years
Put in the years your family were born. You’ll see how many people lived in Nairobi in each of those years, and when each of them turned 30.
Kenya · every city · 2025
Where it is
How to read this: Nairobi is the dot in colour with a ring around it. The grey dots are the other cities of Kenya in 2025, 50 in all, each drawn with an area that matches its people. Countries next door are outlines only.
Area and built-up land · km²
How much land it covers
In 2025, Nairobi covered 638 km², and buildings, roads and other built-up land covered 136 km² of it. That is 22 m² of built-up land for each person, about a square 5 by 5 metres. Since 1975, its built-up land has grown to 4.6 times its size, and its people are 11.4 times as many.
How to read this: the outer pale square stands for all the land the city covers, and the solid square inside it for the part with buildings, roads and the like on it. All three squares share a scale, so you can compare them by eye. A hatched one is a year the UN has projected.
Of every 100 people in Kenya
Its share of Kenya
Of every 100 people in Kenya in 2025, 11 lived in Nairobi, which is 6.1 million people.
How to read this: shrink Kenya to 100 people and this is what you get. The coloured squares are the ones who would live in Nairobi; the grey ones are everybody else, in other cities, in towns and out in the country.
Ranked by people · 2025
Cities of a similar size
In the world, 2025
- 61 Chaozhou China6,407,770
- 62 Amman Jordan6,403,666
- 63 Baghdad Iraq6,390,735
- 64 Chengdu China6,139,874
- 65 Nairobi6,134,334
- 66 Kozhikode India6,123,872
- 67 Shenyang China5,702,638
- 68 Kabul Afghanistan5,635,737
- 69 Onitsha Nigeria5,627,706
In Kenya, 2025
- 65 Nairobi6,134,334
- 348 Mombasa1,456,207
- 955 Nakuru574,091
- 1299 Kisumu430,532
- 1346 Eldoret418,175
- 1720 Garissa333,505
- 2526 Mutuati232,440
- 2983 Kisii200,579
- 3249 Naivasha185,944
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 Nairobi 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 Nairobi 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