The average thickness of the Earth's crust is about 30 kilometers (19 miles).

However, it's important to note that the crust's thickness varies significantly depending on its location:

* Continental crust: This is the thicker type, averaging around 35-40 kilometers (22-25 miles). It can reach up to 70 kilometers (43 miles) under mountain ranges.

* Oceanic crust: This is thinner, with an average thickness of about 7 kilometers (4 miles).

Let me know if you'd like to know more about the different types of crust or their properties!