With Sailor, one digit tells you the nib width — and number five does not exist
Browse a shop listing for Sailor fountain pens and you see the same pen again and again, differing only in the digits at the end. Those digits are not decoration. For Sailor, reading a single one of them tells you the nib width.
Of the last three digits, the first is the nib
Sailor fountain pens carry three digits at the end of the catalogue number. The first is the nib; the other two are the colour.
Cross-referencing every Sailor fountain pen on record, the nib digit maps like this:
- 1 — extra fine
- 2 — fine
- 4 — medium
- 6 — broad
- 7 — zoom, brush
- 9 — music
Larger digit, broader line — a straightforward ladder. That zoom and music nibs have numbers at all says something too: for Sailor these are not exotic special orders but part of the ordinary range.
Nothing is numbered five
The interesting part is the gap. Not one pen carries a five.
Between broad (6) and medium (4) you might expect a medium-broad, but that slot sits empty. Pens numbered 0, 3 and 8 do exist, yet they turn out to be medium-fine, or nibs ground to a stated angle — never a single settled width.
Only six digits map cleanly one-to-one: 1, 2, 4, 6, 7 and 9.
The two colour digits do not travel between series
The colour half is not so obliging. The same number means different colours in different series.
One number meant "polar bear" in one series and "swan" in another. Within a single series the mapping holds; across the brand it does not. There is no colour table that works everywhere.
So colour has to be confirmed by name. Only the nib can be read from a number.
What the number cannot tell you
Pens finished in maki-e lacquer or raden shell often carry no colour name at all — each piece differs, so no code could describe it.
Whether a pen is current or discontinued is also invisible in the number. PencilDB records production status as a separate field, so it can be checked there.
(Compiled from the Sailor fountain pens recorded in PencilDB, August 2026.)