🖋️ Fountain Pens — Gear Guide
Fountain pen nib sizes EF, F, M, B: Western vs. Japanese sizing, what actually changes, and how to choose
The same label means different things on different pens. A medium nib on a Pilot Metropolitan writes about as wide as a fine on a LAMY Safari. Understanding why that gap exists — and what it means for how you choose your first or next pen — is more useful than any size chart alone.
The sizing labels and what they literally mean
Fountain pen nibs are labeled by the approximate width of the line they produce: EF (extra fine), F (fine), M (medium), B (broad), and sometimes BB (double broad) or finer designations like UEF (ultra extra fine) or needlepoint. These refer to the tipping material — typically a small sphere of iridium or a harder rhodium-based alloy — ground and polished to a specific profile at the end of the nib tine.
The key word is "approximate." There's no industry-wide standard that defines, say, that a medium nib must produce a line between 0.5mm and 0.6mm. Each manufacturer sets its own calibration. The labels describe relative widths within a brand's lineup, not absolute measurements across all brands.
This is why someone switching from a Japanese pen to a European pen for the first time often finds the medium nib they ordered writes significantly wider than they expected.
The Western/Japanese divide
Japanese nib manufacturers — primarily Pilot, Sailor, and Platinum — consistently produce nibs that run approximately one full size narrower than equivalent-labeled Western nibs from Pelikan, LAMY, Waterman, Montblanc, and most German or French manufacturers.
The table below shows approximate line widths based on observed measurements across common pen models. Individual units vary — nib grinding is still partly handwork — but these represent reliable central tendencies:
| Label | Japanese approx. line width | Western approx. line width |
|---|---|---|
| EF (Extra Fine) | 0.2–0.3 mm | 0.3–0.4 mm |
| F (Fine) | 0.3–0.4 mm | 0.4–0.5 mm |
| M (Medium) | 0.4–0.55 mm | 0.55–0.7 mm |
| B (Broad) | 0.5–0.7 mm | 0.8–1.1 mm |
The practical conversion is: Japanese Fine ≈ Western Extra Fine; Japanese Medium ≈ Western Fine; Japanese Broad ≈ Western Medium. This is approximate — but it's a better starting point than reading the label at face value when switching brands.
Why the difference exists
The gap comes from the writing systems each tradition was designed for. Traditional Japanese calligraphy — and more practically, everyday handwritten kanji — requires the ability to distinguish complex characters with many strokes in a small space. The stroke density in written Japanese and Chinese demands finer line control than Latin-script writing, where the alphabet has fewer and simpler strokes per character.
When Japanese fountain pen manufacturers developed their sizing conventions in the mid-20th century, they calibrated their nibs for the fine control that Japanese writing required. Western manufacturers calibrated for the stroke weight that looked and felt right for Latin script handwriting on the paper and writing speed conventions of European business and correspondence.
Neither convention is "wrong." They reflect the writing culture they were built for. The problem appears when you assume the labels are interchangeable across traditions — which they're not.
What actually changes between sizes
Moving from EF to F to M to B isn't just a line width change — several other properties shift together.
Line width and ink flow
Wider nibs deliver more ink per stroke because the channel between the tines is wider. A broad nib on the same pen and ink combination will lay down a wetter, more saturated line than a fine nib. This changes how the ink looks: broad nibs make shading inks (inks that show tonal variation across a stroke) much more visible. Shimmer inks (inks with suspended metalite particles) only show shimmer reliably in M and wider nibs — finer nibs often filter out the particles in the feed.
Feedback
Fine nibs, especially EF nibs, have more tactile feedback — a subtle scratchiness as the tines engage the paper tooth. Broader nibs write with less feedback and feel smoother or "wet." Whether you prefer feedback or smoothness is personal; many writers find finer nibs more satisfying for deliberate writing, while broader nibs feel effortless for quick note-taking.
Drying time
More ink means longer drying time. An extra fine nib on a fast-drying ink dries almost immediately. A broad nib on a slow-drying ink may still be wet after 10–15 seconds. For left-handed writers who smear wet ink, starting with a finer nib or a fast-drying ink is a practical accommodation — not a permanent constraint, but a sensible starting point.
Paper sensitivity
Fine nibs are more sensitive to paper quality. On cheap paper, a fine nib will catch on fibers, feather (spread ink into fibers sideways), and bleed through. A medium nib on the same bad paper may write cleanly because the rounder tipping profiles of medium and broad nibs ride over fiber texture rather than catching in it. If you plan to use your pen on copy paper, composition notebooks, or similar office paper, a medium nib will perform more consistently than a fine.
Good fountain pen paper (Leuchtturm, Rhodia, Clairefontaine, Tomoe River) handles all nib sizes well. Cheap paper forgives medium nibs and punishes fine ones.
Other nib grinds beyond the standard sizes
Standard round nibs (EF through B) are the most common, but several specialty grinds are worth knowing about:
Stub nib
A stub nib is ground flat and wide on the tipping material rather than rounded. The result is a nib that produces wider lines when writing horizontally and narrower lines on vertical strokes — similar in principle to italic calligraphy. Stubs are not as sharp as italic nibs; they write smoothly and the line variation is subtle. LAMY's Safari and Al-Star lines offer good mid-range stub nibs. Stub widths are typically labeled 1.1mm, 1.5mm, or 1.9mm rather than F/M/B.
Italic nib
Similar to stub but with sharper corners on the tipping. Italics produce more pronounced line variation than stubs and are used for calligraphic handwriting. The tradeoff is that sharp edges catch more easily on paper, especially at lower quality. True italic grinds are less common in production pens; most are custom nibwork.
Cursive italic (CI)
A compromise between italic sharpness and round nib smoothness. The corners are slightly rounded to reduce catching, while enough edge remains for visible line variation. Some Sailor nibs and custom nibmeisters offer this as a standard offering. Good starting point for people who want line variation without committing to a full italic.
Needlepoint and Japanese EF
The finest available production nibs — 0.2mm and below — used for writing very small kanji or extremely fine-line technical work. Sailor's Naginata Extra Fine and Pilot's Ultra Extra Fine are examples. These nibs are scratchy on most Western paper and must be paired with very smooth, fountain-pen-optimized paper to write comfortably.
How ink interacts with nib size
Nib size and ink choice interact more than most beginners expect. A few specific combinations are worth knowing:
- Shading inks (Diamine Oxblood, Iroshizuku Tsuki-yo, Robert Oster Fire & Ice): shading is only visible in M nibs and wider. A fine nib will show the color but not the tonal variation the ink is made for.
- Shimmer inks (anything containing suspended metalite particles): require M nib minimum, ideally B or wider. Fine nibs filter out the particles in the feed.
- Fast-drying inks (many Pilot Iroshizuku colors, Noodler's Bulletproof): may dry in the feed of fine nibs if the pen is capped for extended periods. Medium and broad nibs have more ink reserve in the channel and recover more reliably after long storage.
- Iron gall inks (Diamine registrar's ink, Rohrer & Klingner Salix): mildly corrosive over time; avoid in fine nibs on cheaper steel unless you flush regularly. Gold nibs or platinum/rhodium-tipped nibs handle iron gall better long-term.
Choosing your first nib size
The most common advice — "start with a medium" — is reasonable for Western pens on good paper. But it assumes you know whether you're buying a Western or Japanese pen, and that you have fountain pen paper available. A more useful starting framework:
- If you write small (tight, small handwriting, dense notes): Japanese Fine or Western Extra Fine. Your letter size dictates line width; cramped writing with a broad nib produces illegible smearing.
- If you write large or normally: Japanese Medium or Western Fine is a safe starting point. Enough ink flow to feel good, narrow enough to be legible on most paper.
- If you write on cheap or bad paper regularly: Medium nib regardless of brand. The forgiving tipping profile outweighs other considerations.
- If you're left-handed with a slow dry time problem: Start finer (Japanese EF or F) and use a fast-drying ink. Adjust from there.
For a first pen, the Pilot Metropolitan is the most consistently recommended option for both Japanese sizing and build quality. The Metropolitan in Fine writes about 0.35mm — a good calibration point to compare against when trying other pens. If that feels too fine, a LAMY Safari or Al-Star in M gives you the Western-medium experience to compare.
Most people who get serious about fountain pens end up with a range of sizes and use them for different tasks — fine nibs for notes and cramped pages, medium for journaling, broad for signatures and display writing. The first pen is an introduction to the spectrum, not a permanent commitment.
Gear actually worth buying
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Pilot Metropolitan (F or M)
The standard beginner recommendation for Japanese sizing. Consistent nib, converter included, writes ~0.35mm in Fine. Most useful calibration point to start from.
LAMY Safari (M or F)
The standard Western sizing entry point. Medium nib writes ~0.6mm. Good comparison pen if you're trying to understand the Japanese/Western gap firsthand.
Sailor Pro Gear (Fine)
Japanese Fine nib in the mid-tier range. Sailor nibs are known for slightly more feedback than Pilot — useful to feel the difference between manufacturers at the same label size.
Rhodia dot pad (A5)
Smooth, fountain-pen-friendly paper. No feathering, minimal bleed-through even with wet broad nibs. The standard test paper for evaluating how a nib actually writes.
Diamine bottled ink
The value ink option — wide range of colors, well-behaved in most nibs. Good way to explore shading colors in medium and broader nibs without spending Iroshizuku prices.