Ballpoint pens generally come under three main categories. Fine ballpoint pens have tips made to write a line that is 0.8 mm thick or less. Medium ballpoint pens have tips made to write a line that is between 0.9 and 1.2 mm thick. Lastly, broad ballpoint pens produce a line that is 1.3 mm or thicker.
There is no right or wrong when it comes to choosing the tip size that is right for you. However, certain people like one over the other and each tip size has its own pros and cons.
Initially, it is worth noting that ballpoint pens usually come in fine and medium tips. Since the ballpoint pen ink is oil-based, it is rather viscous and thick. Understanding how pen work, especially a ballpoint, is key here: unlike a rollerball that pools ink and drags it, the ballpoint pen creates a very uniform line due to its unique mechanism. As a result, ballpoints themselves generally produce thicker lines than rollerballs, so fine and medium tips have become standard for everyday ballpoint usage.