Nib & Paper Compatibility Chart

Nib \ Paper	Copy / printer paper 75 gsm (20 lb bond)	Premium copy / writing paper 90 gsm (24 lb bond)	Fountain-pen journal paper 90 gsm (24 lb bond (Rhodia / Clairefontaine))	Heavy writing / stationery 120 gsm (32 lb bond)	Cardstock / cover 216 gsm (80 lb cover)
Extra Fine (EF) 0.3 mm	Moderate risk	Low risk	Low risk	Low risk	Low risk
Fine (F) 0.5 mm	Moderate risk	Low risk	Low risk	Low risk	Low risk
Medium (M) 0.7 mm	High risk	Low risk	Low risk	Low risk	Moderate risk
Broad (B) 0.9 mm	High risk	Low risk	Low risk	Low risk	Moderate risk
Double Broad (BB) 1.1 mm	High risk	Moderate risk	Low risk	Low risk	High risk
Stub 1.1 mm (1.1) 1.1 mm	High risk	Moderate risk	Low risk	Low risk	High risk
Stub 1.5 mm (1.5) 1.5 mm	High risk	Moderate risk	Low risk	Low risk	High risk

How to read this chart

Bleed-through and feathering happen when a page absorbs more ink than its sizing (the coating that resists ink absorption) can handle in one spot. Two things drive that: how much ink the nib puts down, and how well the paper resists it. This chart multiplies those two known quantities together instead of guessing at either alone.

Read it as a shortlist, not a verdict. “Low risk” combinations are safe defaults for double-sided writing with almost any ink. “Moderate risk” is fine for most everyday inks but worth a quick test page with a new bottle. “High risk” combinations can still work — just expect some show-through, plan on single-sided pages, or reach for a drier ink.

The two calculators behind this chart go deeper on each half: the Nib Size Guide for line widths and what each size is good for, and the Paper Weight & GSM Guide for gsm conversions and per-stock notes.

❓ Frequently Asked Questions

How is the risk rating calculated?

It combines two things already published on this site: the paper stock's own fountain-pen friendliness (poor/fair/good/excellent, from the Paper Weight & GSM Guide) and the nib's line width (from the Nib Size Guide). Wider, wetter nibs push the rating up; finer nibs pull it down. It's a transparent, rule-based estimate, not a lab measurement.

Is a 'High risk' combination unusable?

No — it just means feathering, ghosting, or bleed-through is more likely, so you'll want to test a page first, use a drier ink, or write on one side only. A broad or stub nib on 75 gsm copy paper is the classic High risk combination that surprises new fountain-pen users.

Why does the same paper rate differently for different nibs?

Because bleed-through is really about how much ink lands on the page, not just the paper. A fine (EF) nib lays down a thin, light line even on middling paper, while a broad or stub nib lays down several times more ink on the same spot — so the same 90 gsm sheet can be safely Low risk with a Fine nib and Moderate risk with a Double Broad.

Does this account for ink wetness or saturation?

Not directly — the chart only uses nib width and the paper's general fountain-pen rating. A very wet, heavily saturated ink (or a very dry one) will shift real-world results up or down from the estimate, which is why it's a planning guide, not a guarantee.