Brand-to-brand nib converter
Pick the nib you have (or want). The tool finds the closest grade in every other brand by measured millimeter width - the honest way to answer “what is a Pilot fine in Lamy?”
Millimeters ↔ inches
Tip: nib tipping is sometimes measured with calipers in inches - 0.028″ is about 0.71 mm, roughly a Western fine.
Fountain pen nib size comparison chart (mm)
Curated approximate written-line widths per brand and grade. Filter by origin to see the Japanese-vs-Western gap at a glance.
Line-width lab: see nib sizes at true scale
Add up to 4 nibs (or a custom width) and compare their real line widths side by side, each with a writing sample drawn at the same width.
Calibrate for true physical size
Screens lie about millimeters. Hold a ruler against the bar below and drag the slider until the bar measures exactly 50 mm on your ruler. The renderer then draws lines at true physical width.
Stub & italic nib guide
A stub or italic nib has a flat, broad edge: a wide downstroke and a thin cross-stroke. Pick a size to see both strokes at true scale.
Stub vs italic - the practical difference
Both are flat broad-edge nibs. Stub nibs have softened, slightly rounded corners - forgiving enough for everyday writing. Italic nibs have crisp, sharp corners for maximum downstroke/cross-stroke contrast in formal calligraphy, but they punish any rotation of the pen with skipping. Many products blur the words: Lamy's 1.1/1.5/1.9 “italics” write like smooth stubs for most people.
Nib grades decoder
What the letters stamped on a nib actually mean — all the common fountain pen nib grades decoded below, with nib grades explained through typical written-line ranges and who each grade suits.
Fine vs medium - the eternal question
The medium vs fine nib debate is the most common sizing question in the hobby. Fine (about 0.3-0.6 mm): small handwriting, fast notes, cheap paper, CJK characters. Dries fast, stays legible. Medium (about 0.45-0.8 mm): the default most pens ship with - smoother feel, shows ink shading, suits average-to-large handwriting on good paper. Still torn? Remember a Japanese medium writes like a Western fine, so check the brand charts before buying.
Fountain pen nib questions, answered
Is a Japanese fine nib the same as a Western extra fine?
What is the best nib size for a fountain pen?
What is the smoothest fountain pen nib?
Should I choose a medium or fine nib?
What do EF, F, M, B, and BB mean on a fountain pen nib?
Are Lamy nib sizes the same as Pilot nib sizes?
How wide is a medium nib in millimeters?
What is the thinnest fountain pen nib you can buy?
What is a stub nib, and what does 1.1 stub mean?
What is the difference between a stub nib and an italic nib?
Do Japanese nibs really write finer than European nibs?
Which nib size is best for small handwriting or cheap paper?
Can I swap a nib from one brand onto another brand's pen?
Why does my medium nib write wider than my friend's medium?
Which nib size shows off ink shading and sheen best?
Are the millimeter widths on this page exact?
How the Japanese-to-Western nib conversion works
Nib grade letters (EF, F, M, B) are brand-relative labels, not measurements - no international standard defines how wide a “fine” must be. The converter on this page works the honest way: every brand/grade pair maps to a curated approximate line width in millimeters, and conversion means finding the grade in the target brand whose width is closest to your source nib. The classic rule of thumb - Japanese nibs run about one grade finer than Western nibs - falls out of the data automatically: a Pilot F at about 0.40 mm lands exactly on a Lamy EF at about 0.40 mm.
Where the millimeter numbers come from
All widths are approximate, curated from public sources: measurement threads on the Fountain Pen Network (including caliper and optical-comparator readings shared by community members), retailer nib guides (the common European nominal scale of EF 0.4 / F 0.6 / M 0.8 / B 1.0 mm), and the widely documented Japanese-vs-Western offset. Individual nibs vary with sample, ink flow, paper absorbency, and writing pressure - use these numbers to compare brands and choose a size confidently, not as engineering specifications.
Why your screen can show true line widths
The line-width lab renders strokes at real physical size using a pixels-per-millimeter factor. Because operating systems only guess your screen's pixel density, the page includes a ruler calibration step: hold a physical ruler to the 50 mm reference bar and adjust until it matches. Your calibration is saved in your browser, so the renderer stays true-scale on return visits.
Nib size chart by brand: the medium-column quick reference
If you landed here looking for a Lamy nib size chart, a Pilot nib size chart, a Sailor nib size chart, a Platinum nib size chart, a TWSBI nib size chart, a Kaweco nib size chart, a Montblanc nib size chart, or a Parker nib size chart — good news: every one of those brand charts is built into this page. Think of the whole page as a fountain pen nib comparison chart across 12 brands, with the full grade lineup per brand in the Brand Charts tab. For the fastest comparison, this single-column nib size chart shows the one grade every brand sells — medium — with its approximate line width. It doubles as a compact nib size converter chart: find your current nib's row, note its width, and scan for the closest match in the brand you are shopping.
| Brand | Medium nib ≈ mm | Origin |
|---|---|---|
| Sailor | ≈0.45 mm | Japan |
| Platinum | ≈0.50 mm | Japan |
| Pilot | ≈0.58 mm | Japan |
| Parker | ≈0.70 mm | USA |
| JoWo | ≈0.75 mm | Germany |
| Lamy | ≈0.75 mm | Germany |
| Montblanc | ≈0.75 mm | Germany |
| TWSBI | ≈0.75 mm | Taiwan |
| Bock | ≈0.80 mm | Germany |
| Faber-Castell | ≈0.80 mm | Germany |
| Kaweco | ≈0.80 mm | Germany |
| Pelikan | ≈0.90 mm | Germany |
Full EF–BB lineups are in the Brand Charts tab. Every nib size in mm on this page is an approximate written-line width: individual nibs vary with ink, paper, and pressure.
Fountain pen line width, and the Japanese offset
Fountain pen line width — the fountain pen nib line width in millimeters, or fountain pen point size by another name — is simply the thickness of the ink line a nib lays down. Because Japanese nibs run about one grade finer than Western ones, the fountain pen nib size difference between a Japanese medium and a Western medium can reach 0.3–0.45 mm — a clearly visible gap. That is why this page works as a Japanese to Western nib size converter: instead of translating grade letters, it translates measured fountain pen line thickness in mm. Use the converter tab for exact per-brand matches, or the line-width lab to see any width drawn at true physical scale — a living fountain pen line width chart you can calibrate with a ruler.
These fountain pen nib widths are curated approximations from public community measurements, not manufacturer specifications — plenty accurate for choosing between a fine and a medium, which is what most shoppers actually need.
Frequently asked questions
The same questions live in the FAQ tab above; they are repeated here for easy reading.