Helsinki itself is only 600,000 people, but Helsinki has fused into a single big city with the neighboring municipalities of Espoo and Vantaa (and a bunch of smaller ones), and the total population exceeds one million people.
The OKC metro is also 1.5 million people. The two are very comparable by population/size. It doesn't detract from the point that Helsinki isn't a large city. I'm giving regional context to Americans that if you don't consider OKC large, you shouldn't consider Helsinki large.
It's fair to bring this up, but it's also worth noting that a medium fish in a small pond has a different experience than a medium fish in a big pond. A third of all the people who live in Finland live in Helsinki.
