The thickness of paper corner protectors can vary depending on the specific requirements and the level of protection needed. However, there are some commonly used thicknesses for paper corner protectors in packaging and shipping applications. These thicknesses typically range from 2mm to 8mm.

Here are a few examples of commonly used thicknesses for paper corner protectors:

1. 2mm: This is a thinner option used for lighter-weight items or when minimal corner protection is needed. It provides basic protection against minor impacts and abrasion.

2. 3mm: This is a common thickness for general-purpose paper corner protectors. It offers moderate protection and is suitable for a wide range of products in various industries.

3. 5mm: This thickness provides enhanced protection for heavier items or when extra reinforcement is required. It offers greater strength and rigidity to withstand more significant impacts and compression forces.

4. 8mm: This is a thicker option used for heavy-duty applications or when maximum corner protection is necessary. It provides robust protection for fragile or high-value items during transit or storage.

It's important to note that these thicknesses are general guidelines, and the specific requirements may vary based on the size, weight, fragility, and transportation conditions of the packaged items. The choice of thickness should be based on a careful assessment of the specific needs and potential risks to ensure adequate protection during handling and shipping.