Most people will never know

There are several reasons why pen caps have holes, each contributing to the overall functionality and safety of the pen. These reasons include safety and prevention of choking hazards, pressure equalization to ensure smooth ink flow, manufacturing and cost efficiency, and aesthetic considerations. Each of these factors plays a role in the decision to include a hole in the pen cap design.

One of the primary reasons for the hole in pen caps is safety. Small objects like pen caps can pose a choking hazard, especially for children. The hole in the cap allows air to pass through, reducing the risk of suffocation if the cap is accidentally swallowed. This safety feature has become a standard in pen design, following guidelines set by safety organizations to prevent choking incidents.

Another important reason for the hole in pen caps is pressure equalization. When a pen is capped, changes in temperature or altitude can cause pressure to build up inside the pen. The hole allows air to flow in and out, preventing pressure build-up that could cause ink to leak or flow inconsistently. This ensures a smooth writing experience and helps maintain the pen’s performance over time.