Nib Width Calculator — Perfect Nib for Your Letter Height

The nib width ratio is the number of nib widths that make up the x-height (the height of lowercase letters like a, e, o). It comes from the broad-edge "nib-width ladder": you step the chisel-cut nib up the page, corner to corner, to mark out the height. Italic uses 5 nib widths, so the x-height equals 5 times the nib width.

No. Copperplate, Spencerian and modern pointed-pen scripts use a flexible pointed nib (Gillott 303, Hunt 101, Brause EF66), not a broad edge, so they have no fixed nib width to step up the page. Their proportions are set as a ratio of the chosen x-height — Copperplate is typically 3:2:3 (ascender:x-height:descender) — and you simply pick an x-height you can write comfortably. Use a slant-and-proportion guide for those hands, not a nib-width calculator.

Standard broad-edge nibs (Brause, Mitchell Round Hand, Speedball C-series) run from about 0.5 mm to 6 mm. Common widths: 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 5 mm and 6 mm. Choose the nearest available size to your calculated width — or adjust your x-height to match a nib you already own.

Ink the nib and lay down a short horizontal stroke (the full edge flat on the paper), then measure that stroke with a ruler — that is your true nib width. Manufacturer labels vary, so a measured stroke is more reliable than the printed size.

Round to the nearest available nib size. Going slightly smaller gives lighter, more open letters; slightly larger gives a bolder, heavier weight. You can also nudge your x-height up or down to land exactly on a nib you have.

Absorbent paper lets ink spread and feather, making strokes read wider than the nib edge. On smooth, sized paper like Rhodia or Clairefontaine the stroke matches the nib width closely. On textured or absorbent stock, expect a heavier line and consider sizing the paper or stepping down a nib.