The pen thickness specifications are B, M, FM, F and EF. The thickness specifications of the pens used in daily use in Chinese are F or EF.

Font pen nibs vary from fine to thick. Generally, the most common pen nib sizes are B (Broad), M (Medium), and FM (Fine-Medium). , F (Fine) and EF (Extra-Fine) are the main ones, from coarse to fine they are B > M > F > EF.

The size of the pen tip varies slightly from pen manufacturer to pen manufacturer. In the same size unit, the nib of Japanese fountain pens will be thinner than that of European fountain pens.

According to normal writing habits, Westerners mostly use the M nib when using fountain pens, and use the B nib when signing. Because the strokes in Chinese writing are complicated, F or thinner EF pen tips can generally be used.

Extended information

There are mainly five common nib sizes for fountain pens, from thin to thick:

1. EF=XF=Extra Fine nib The width is about: 0.24mm~0.28mm.

2. F=Fine pen tip width is about: 0.28mm~0.34mm.

3. M=Medium The width of the pen tip is about: 0.34mm~0.44mm.

4. B=Broad pen tip width is about: 0.44mm~0.54mm.

5. BB=Double Broad The width of the pen tip is about 0.66mm~0.86mm.

There are also more subdivided nibs, such as EEF which is thinner than EF, 3B (Triple Broad) which is thicker than BB, and MF nib which is between F and M. Although different brands have different definitions of pen tip size (the M tip of M brand is written as thicker or thinner than the P brand), the width of the pen tip is mostly between 0.18mm~0.86mm.

In order to suit personal writing preferences, some manufacturers also have oblique nibs, such as: OM=Oblique Medium OB=Oblique Broad OBB=Oblique Double Broad.

Baidu Encyclopedia--Fountain Pen

Baidu Encyclopedia--Fountain Pen Nib