Here's a breakdown of the Earth's layers by thickness:

1. Mantle: The mantle is the thickest layer, extending from about 30 km (19 miles) below the Earth's surface down to about 2,900 km (1,800 miles).

2. Outer Core: This layer is about 2,200 km (1,400 miles) thick.

3. Inner Core: This is the Earth's densest layer and measures around 1,220 km (760 miles) thick.

4. Crust: The Earth's outermost layer is the thinnest, ranging from 5 to 70 km (3 to 44 miles) in thickness.