A standard 80gsm A4 piece of paper is exactly 0.1mm thick. So when levelling your bed, it must be almost zero resistance, or use a thicker piece of paper! : r/ender3
The Print Guide: Paper size and weight conversions
US Paper Sizes Explained. The difference between A4 and Letter. | Doxdirect
A4 Paper Size - What Size Is A4 Paper? | Complete Guide to Paper Sizes