Skyscrapers and Slums: What's Driving Mumbai's Housing Crisis?

What is the floor space index? It’s a ratio tool used by cities around the world to regulate the maximum amount of floor space that can be built on a given plot of land.

For example, if you have a one square meter plot of land and the FSI is 1, you can build one square meter of floor space. You can decide if you’ll cover the whole plot with a 1-story building, half the plot with a 2-story building, and so on.

In most densely populated cities, the FSI is typically high to allow for lots of building up. That’s why huge cities with limited land space (think New York City, Singapore, Hong Kong) have such tall skyscrapers. The FSI in Singapore can be as high as 25, meaning that your one square meter plot of land could hold a 25-story building.

In India, however, FSIs tend to be quite low. Mumbai – a very densely populated city located on a small peninsula – boasts a maximum FSI of just 1.3. Mumbai can’t sprawl outwards because of limited availability of land. And it also can’t grow upwards.

What do these restrictions mean for the people living in Mumbai? They drive housing prices and the cost of living up. It also means less living space. The average living space per person in Mumbai is just 48 square feet. I contrast, the United States federal government mandates a minimum of 50 square feet per person in prison cells.

This low FSI in Mumbai, which drops down to 1 in suburban areas, also contributes to the extensive slums in and around the city. We’ll cover these unintended consequences in more detail in this video.