How many buildings are there in the world?
Nobody counted buildings until machine learning made it possible to detect them from satellite imagery, and the answers still differ by more than a factor of two depending on what counts as a building. Google's Open Buildings dataset alone identified about 1.8 billion structures across Africa, South Asia, South-East Asia and Latin America. Microsoft has released comparable footprint datasets for North America and Europe. The disagreement is definitional: a rural compound of five outbuildings can be detected as one structure or five, and informal settlements are the hardest case of all.
How the figure is arrived at
A convolutional model is trained on hand-labelled satellite tiles to output building footprint polygons, then run across imagery of the whole land surface. Accuracy is measured against manually labelled validation tiles. Detection is good for isolated buildings with clear shadows and poor for dense low-rise districts where roofs merge.
How confident it is
- Low estimate
- 1,500,000,000
- High estimate
- 4,000,000,000
- Spread
- 2.7× between the bounds
Other things people built counts
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many books have ever been published? about 130 million as of 2010 — probably over 200 million now
- How many airports are there in the world? about 45,000 with runways — but only around 4,000 with scheduled airline service
- How many ATMs are there in the world? about 3 million
- How many cities are there in the world? about 10,000 with over 50,000 people; 33 megacities over 10 million
- How many computers are there in the world? roughly 2 billion personal computers in use
- How many miles of road are there in the world? about 64 million km — roughly 40 million miles
Common questions
- How many buildings are there in the world?
- somewhere between 1.5 and 4 billion
- How is that estimated?
- A convolutional model is trained on hand-labelled satellite tiles to output building footprint polygons, then run across imagery of the whole land surface. Accuracy is measured against manually labelled validation tiles. Detection is good for isolated buildings with clear shadows and poor for dense low-rise districts where roofs merge.
Related pages
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many people are there in the world? Living things and the natural world
- How many stars are there in the universe? Space and the universe
- How many bones are in the human body? The human body
- How many grains of sand are there on Earth? Living things and the natural world
- How many ants are there in the world? Living things and the natural world
- How many trees are there in the world? Living things and the natural world
Sources
- Typical range compiled from manufacturer specifications — At One Place