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Depending on whether the term “city proper,” “urban area,” or “metropolitan area” is used, the number of people living in a city can vary greatly. When comparing cities, this discrepancy frequently causes confusion. That is why I found the approach adopted by Reddit user Frierfjord1 very wise. By using 30km population circles centered on city centers, he offers a standardized method to compare Europe’s largest cities.
To create his map, Frierfjord1 utilized data from Population Around a Point, which is based on the Global Human Settlement Layer (GHSL) population grid for 2025. This approach prevents the confusion that occurs due to variations in definitions of metropolitan and urban regions. An urban area is generally taken to be the built-up contiguous part of a city, whereas a metropolitan area refers to the urban area along with the surrounding commuter belts. Definitions can differ between countries, hence comparisons are hard to make.
Below is a table comparing the top 10 European cities based on Frierfjord1’s 30km population circles, alongside their respective urban and metropolitan area populations:
Rank
City
30 km Population
Urban Area Population
Metro Area Population
1
Moscow
15.3M
13.0M
21.5M
2
Istanbul
13.3M
15.5M
15.5M
3
London
11.2M
9.5M
14.9M
4
Paris
10.4M
11.1M
12.6M
5
Madrid
6.9M
3.4M
7.0M
6
Saint Petersburg
5.7M
5.6M
6.4M
7
Barcelona
5.4M
4.6M
5.8M
8
Ruhr Area
5.3M
5.1M
5.1M
9
Milan
4.9M
3.1M
4.3M
10
Berlin
4.4M
3.6M
6.1M
Note: The Ruhr Area is polycentric, making it challenging to define a single urban or metro area population.
Of note in this regard is the position of Istanbul. Though often considered Europe’s most populous city, approximately 35% of its inhabitants inhabit the Asian side. Even not counting this part, Istanbul would rank in the top 10 with approximately 8.8 million inhabitants on the European side.
This method of using 30km population circles provides a more stable base for comparison, reducing the inaccuracy caused by varying definitions and administrative boundaries.
Feel free to share your thoughts and ideas in the comments below.
