🖋️ Fountain Pen Nib Size Guide
A quick reference to fountain-pen nib sizes and their line widths — pick a size to see what it’s good for, or work backwards from the line width you want.
🖋️ Medium (M)
The most popular size — smooth general writing and signatures with a touch of shading.
Closest round nib to 0.5 mm: Fine (F) at 0.5 mm.
| Nib | Line width | Best for |
|---|---|---|
| Extra Fine (EF) | 0.3 mm | Tiny handwriting, cramped forms and planners, fine detail, and paper prone to bleed. |
| Fine (F) | 0.5 mm | Everyday note-taking and journaling; a safe all-rounder on cheaper office paper. |
| Medium (M) | 0.7 mm | The most popular size — smooth general writing and signatures with a touch of shading. |
| Broad (B) | 0.9 mm | Bold signatures and short-form writing that shows off ink shading and sheen. |
| Double Broad (BB) | 1.1 mm | Very bold, wet lines with maximal shading; best on premium, ink-resistant paper. |
| Stub 1.1 mm (1.1) | 1.1 mm | Everyday italic flair — thin cross-strokes, thick down-strokes, easy line variation. |
| Stub 1.5 mm (1.5) | 1.5 mm | Headings, envelopes, and expressive calligraphic writing with dramatic line variation. |
Japanese nibs (Pilot, Sailor, Platinum) run about one size finer than Western nibs — a Japanese Medium writes roughly like a Western Fine, so size down a notch if you like a thinner line.
Line widths are approximate — nibs are hand-finished and vary with brand, ink flow, paper, and the angle you write at.
Choosing the width that fits your hand
Nib width shapes everything about how a pen feels and looks. Finer nibs suit small handwriting, detailed work, and thin or cheap paper that would otherwise bleed; broader nibs glide, write wetter, and show off the shading and sheen that make fountain-pen inks special.
The single most useful thing to remember is the Japanese-versus-Western difference: the same letter on the nib means a finer line from Pilot, Sailor, or Platinum than from a European or American maker. When in doubt, match the line width you want rather than the letter stamped on the nib.
❓ Frequently Asked Questions
What do EF, F, M, B, and BB mean on a nib?
They are line widths: Extra Fine (EF), Fine (F), Medium (M), Broad (B), and Double Broad (BB). Roughly, a Western EF lays down about 0.3 mm, F about 0.5 mm, M about 0.7 mm, B about 0.9 mm, and BB about 1.1 mm. Wider nibs write bolder, wetter lines that show more of the ink's shading and sheen.
Which nib size should a beginner choose?
Medium is the most popular all-rounder — smooth, forgiving, and a nice balance of line width and ink flow. If you write small, take a lot of notes, or use cheaper paper that bleeds, a Fine (or a Japanese Medium, which writes like a Western Fine) is the safer pick.
Are Japanese nibs really finer than Western ones?
Yes — as a rule of thumb, Japanese nibs from Pilot, Sailor, and Platinum run about one size finer than their Western equivalents. A Japanese Medium writes roughly like a Western Fine, so if you like a thinner line, size down a notch when buying Western, or up a notch when buying Japanese.
What is a stub or italic nib?
A stub or italic nib is ground so it writes a thick down-stroke and a thin cross-stroke, giving your writing built-in line variation and a calligraphic look. A 1.1 mm stub is an easy everyday choice; a 1.5 mm stub is bolder and better for headings, envelopes, and expressive writing.