How large is a massive galaxy cluster compared to the Milky Way?

Millions of light-years across

Galaxy clusters represent colossal structures containing hundreds to thousands of galaxies bound gravitationally. A massive cluster spans several million light-years across its diameter. To provide context for this immense scale, the Milky Way galaxy, which is considered large itself, measures only about 100,000 light-years in diameter. This means a cluster is orders of magnitude larger than a single galaxy like our own, encompassing an area so vast that comparing it to the Milky Way scaled down to a coin would mean that the cluster covers the area of thousands of those coins spread across a continent. This enormous size necessitates immense gravitational binding, primarily provided by dark matter.