Fountain Pen Nib Width & Paper Ruling Visualizer

A proportional planning tool

Compare your measured lines with your paper

Enter measured or published line widths to compare their proportions with your ruling and writing height. The starting values are illustrative inputs, not nib measurements or recommendations.

Use a decimal point (for example 0.45), ASCII digits and up to 6 decimal places. No commas, grouping, spaces, signs or exponents. All ranges include their endpoints.

1. Paper & writing height Ruling unit

1 inch = exactly 25.4 mm. Changing unit clears the ruling field; re-enter it in the selected unit.

Optional paper-spacing preset Distance between paper rules

1–30 mm after conversion. Presets set millimetres; measure your own paper.

Lowercase body / x-height (mm)

0.1–30 mm. Height of the lowercase body without ascenders or descenders.

Total writing height (mm, optional)

0.1–60 mm, at least the body height. Ascender + body + descender total. Blank uses body height only and excludes any additional height.

2. Your line-width candidates

Use 1–4 measured or published widths, each 0.01–5 mm. Labels are optional, up to 60 characters. Order is preserved.

Nominal EF/F/M/B labels vary by maker and individual nib. Ink, paper, angle, pressure, speed and measurement method also affect the line. This tool does not convert those labels into widths.

Your proportions

Candidate measurements and ratios (same paper and body height for every row)
Candidate	Line width (mm)	Width / ruling

Ratios are rounded to 2 decimal places, half away from zero; millimetre values are exact. Negative clearance means the requested total height exceeds one ruling interval.

What this view can tell you

The width-to-ruling ratio is line width ÷ ruling × 100%. The body-height ratio is body height ÷ ruling × 100%. Remaining vertical clearance is ruling − total writing height.

These are neutral geometric strokes, not simulated handwriting. On-screen physical size is not reliable. The diagram does not locate actual ascenders or descenders.

The tool cannot predict exact line width, feathering, bleed, wetness, shading, handwriting appearance or compatibility. Test the real combination. No brand ranking, endorsement or recommendation is implied, and Alex does not validate these exact outputs.

Inputs and labels stay in this page’s current memory and disappear on reload. Copy transfers the summary to your clipboard only when you request it. No input is sent or saved.

About the paper-spacing presets

5 mm is an example grid or dot interval (Kokuyo Campus grid and Rhodia dotPad). Kokuyo lists 6 and 7 mm horizontal ruling in its Campus range and an 8 mm Campus notebook (NO-205UN). These examples support neutral spacing values, not universal ruling standards or product recommendations.

Sources: Kokuyo Campus Loose Leaf and official product specifications 14259 and 7889; Rhodia dotPad. Confirm the spacing on your own sheet.

Continue from your comparison

Put the proportions into context

Use the result as a starting point, then check the writing, nib, and paper variables that geometry alone cannot decide.