If you’ve been researching fountain pens for any length of time, you’ve probably noticed that every pen comes with a nib size designation — EF, F, M, B, and a handful of specialty options beyond those. It sounds simple enough, but choosing the wrong nib size can turn a beautiful writing experience into a frustrating mess of blobs, scratches, or lines so thin they’re barely visible. I’ve tested over 200 fountain pens across dozens of nib sizes, and I can tell you that nib size is one of the most important decisions you’ll make as a pen enthusiast.
This fountain pen nib guide breaks down every major nib size, explains who each one is best suited for, covers the critical differences between Japanese and European sizing conventions, and gives you a clear path to choosing your first nib with confidence.
What Nib Size Means: It’s All About Line Width
A nib size refers to the width of the line it lays down on paper. That’s it — at its core, it’s a measurement of the ink line your pen produces. But the implications ripple out into everything: how your handwriting looks, how much ink your pen lays down, whether your writing stays legible on small paper, and how expressive your script can be.
Nib sizes run roughly from Extra Fine (EF) on the narrow end to Broad (B) and beyond — with Double Broad (BB), Triple Broad, and stub/italic options pushing even wider. The exact line width in millimeters varies considerably by brand and country of origin, which we’ll cover in the Japanese vs. European section below.
It’s also worth noting that nib size affects more than just line width. Broader nibs tend to lay down more ink, which means they show off shading and sheen in your inks more dramatically. Finer nibs are more controlled, better for small handwriting and precise work, but they can feel scratchier on lower-quality paper.
Extra Fine (EF) — Who It’s For
Extra Fine nibs produce the thinnest lines in the standard range — typically around 0.3–0.5mm depending on the manufacturer. They’re surgical in their precision and work best for people who write small, need highly legible output on lined paper with tight spacing, or prefer a pen that feels more like a fine-point ballpoint or rollerball.
EF nibs are popular with engineers, architects, journalers who fill pages with tiny handwriting, and people filling out forms. They’re also a solid choice if you’re used to ballpoints or fine-tip gel pens and aren’t ready to commit to the lushness of a broader line.
The downsides: EF nibs are unforgiving. A rough paper surface that would barely register with a Medium nib can feel like sandpaper under an EF. They also require higher-quality, well-tuned nibs — a poorly tuned EF is scratchy and skips constantly. If you’re buying your first fountain pen, an EF isn’t always the best starting point unless you genuinely write tiny.
Be aware that Japanese EF nibs are significantly finer than European EF nibs — a Japanese EF can approach 0.3mm, which borders on mapping pen territory.
Fine (F) — The Most Popular Choice
Fine is the most popular nib size sold globally, and for good reason. It strikes a balance between control and expressiveness that works for the widest range of writers. A Fine nib in a Japanese pen typically runs 0.4–0.5mm; in a European pen, closer to 0.6–0.7mm.
Fine nibs work on most papers — even cheaper copy paper — without excessive feathering or bleed-through. They’re legible at normal handwriting sizes, show moderate ink shading, and feel responsive without being scratchy. For people who write with moderate pressure and average-sized letters, Fine is the sweet spot.
If you’re buying your first serious fountain pen, a Fine nib is probably your safest bet. The Pilot Metropolitan is one of the most recommended starter pens in the fountain pen community, and its Fine nib is a perfect introduction — smooth, consistent, and refined enough to make ink colors pop without demanding premium paper.
Medium (M) — Smooth and Expressive
Medium nibs are where fountain pens start to feel like fountain pens. The broader line — typically 0.6–0.8mm in Japanese pens, 0.8–1.0mm in European — lays down enough ink to show off a good ink’s shading, sheen, and color depth in a way that finer nibs simply can’t match.
Medium nibs glide. Where a Fine nib requires some feedback to feel satisfying, a Medium nib in a well-made pen floats across the page with minimal resistance. They’re forgiving of slight misalignment, responsive to writing angle changes, and generally the most pleasant size to write with for long sessions.
The trade-off is paper sensitivity. Medium nibs lay down enough ink that cheap paper will feather and bleed noticeably. You’ll want to pair a Medium nib pen with fountain pen-friendly paper — Rhodia, Clairefontaine, Leuchtturm, or similar.
The Pilot Metropolitan in Medium is a great way to experience what a smooth, wet medium nib feels like at an accessible price. Once you’ve written with a well-tuned Medium, it’s hard to go back.
Broad (B) — Showpiece Nibs
Broad nibs are for people who write large, love dramatic ink expression, and aren’t afraid to commit to premium paper. European Broad nibs can lay down lines over 1mm wide — they’re bold, ink-hungry, and visually striking on the page.
Broad nibs are showpieces. The right ink in a well-tuned Broad nib will sheen, shade, and shimmer in ways that make onlookers stop and ask what you’re using. Broad nibs are popular for signatures, header writing, journaling on larger paper, and as dedicated ink-testing pens.
They’re not great everyday workhorses for most people. The wide line is harder to control, takes longer to dry (increasing smearing risk, especially for left-handers), and demands paper that can handle serious ink saturation. But as a second or third pen in your collection — particularly dedicated to a beautiful shading ink — a Broad nib is deeply satisfying.
Specialty Nibs: Italic, Stub, and Flex
Beyond the standard size range, there are several specialty nib types worth knowing about.
Italic nibs have a flat, rectangular tip that produces dramatically varying line widths depending on writing direction — thin on upstrokes, wide on cross-strokes. They’re used for calligraphy and expressive writing but require more deliberate technique and are less forgiving of non-standard writing angles.
Stub nibs are similar to italics but with slightly rounded corners, giving you the line variation of an italic with considerably more forgiveness. Stubs are great for people who want more expressive writing without full calligraphic discipline. The Lamy Safari and Al-Star can be ordered with stub nibs and are excellent entry points into this category.
Flex nibs allow the nib to spread apart under pressure, creating dramatic line width variation between light strokes and pressed strokes. Vintage flex nibs (particularly Waterman and Mabie Todd from the early 20th century) are prized collector items. Modern flex nibs exist at various price points, though truly responsive flex tends to appear in higher-end or vintage pens.
Japanese vs. European Sizing: The Critical Difference
This is the most common source of confusion for new fountain pen buyers: Japanese nibs run significantly smaller than European nibs of the same stated size.
A Japanese Fine is roughly equivalent to a European Extra Fine. A Japanese Medium is roughly equivalent to a European Fine. This means if you’re used to European pens and pick up a Japanese Fine expecting the same line width, you’ll be surprised by how much narrower it writes.
Here’s a rough equivalency table:
- Japanese EF ≈ 0.3mm — exceptionally fine
- Japanese F ≈ 0.4–0.5mm ≈ European EF
- Japanese M ≈ 0.6mm ≈ European F
- Japanese B ≈ 0.7–0.8mm ≈ European M
- European M ≈ 0.8–1.0mm
- European B ≈ 1.0–1.2mm
Major Japanese brands include Pilot, Platinum, and Sailor. Major European brands include Lamy (German), Pelikan (German), Montblanc (German), Waterman (French), and Conway Stewart (British). When shopping cross-brand, always look for reviews and line width swab comparisons rather than relying solely on the size designation.
How to Choose Your First Nib
With all of this in mind, here’s a practical framework for choosing your first nib.
Start by looking at your handwriting size. If you write small and tight, lean toward Fine (or even EF). If you write large and loopy, Medium or Broad will feel more natural and expressive.
Consider your paper situation. If you’re using notebooks from the drugstore or standard printer paper, stick with Fine — it’s the most forgiving. If you’re willing to buy fountain pen-friendly paper, open yourself up to Medium or Broad.
Think about what you want from the ink. Fine nibs are about control and legibility. Broad and Medium nibs are about ink expression — shading, sheen, depth of color. If you want to see what an ink really looks like, go broader.
For most beginners, a Fine or Medium in a Japanese brand is the ideal starting point. The Lamy Safari is another perennial recommendation — it’s available in EF, F, M, and B nib options (sold separately as swap-out steel nibs), making it one of the most flexible starter pens on the market. You can buy one body and experiment with multiple nib sizes affordably.
If you want a Japanese starter, the Pilot Metropolitan in Fine or Medium is hard to beat for the price. Both the Safari and the Metropolitan are under $30 and represent thousands of community-hours of positive testing across all skill levels.
Conclusion
Nib size is personal, but it doesn’t have to be mysterious. Extra Fine for precise small writing, Fine for everyday versatility, Medium for smooth ink expression, Broad for drama and display — each size has a place in a well-rounded collection. Specialty nibs like stubs, italics, and flex open up artistic possibilities that standard sizes can’t match.
Remember the Japanese vs. European sizing difference, don’t be afraid to start with Fine or Medium, and treat your first few pens as experiments. You’ll develop strong opinions quickly once ink hits paper. That’s half the fun.
Happy writing.