MEASUREMENT

Understanding Graph Paper Sizes and Grid Spacing

A graph paper generator is only as useful as its units. If page size, spacing, and export dimensions disagree, a ruler will not match the labelled grid. Gridline Atelier uses millimetres internally, converts US Letter with 1 inch = 25.4 mm, and writes those millimetres onto the SVG. This article collects the numbers the workshop actually uses.

Follow along in the free graph paper generator. The live readouts labelled page width, page height, printable width, and printable height should match the arithmetic below.

US Letter dimensions

US Letter is 8.5 inches by 11 inches. Width in millimetres: 8.5 × 25.4 = 215.9 mm. Height: 11 × 25.4 = 279.4 mm. Portrait uses 215.9 mm wide and 279.4 mm tall. Landscape uses 279.4 mm wide and 215.9 mm tall. The generator swaps those two values; it does not invent a third size and it does not change grid spacing when you rotate the page.

A4 dimensions

A4 is defined as 210 mm by 297 mm. Portrait: 210 mm wide, 297 mm tall. Landscape: 297 mm wide, 210 mm tall. A4 is a few millimetres narrower and a few millimetres taller than Letter in portrait. A pattern that just fits 39 cells of 5 mm on Letter’s printable width may fit a different leftover sliver on A4. Always generate for the stock you will load.

Millimetres versus inches

The conversion is fixed: 1 inch = 25.4 mm. There is no “desktop publishing inch” in this project and no 25 mm approximation. If you think in inches, divide millimetres by 25.4. A 5 mm cell is 5 / 25.4 ≈ 0.197 in, a little under 1/5 inch. A 10 mm cell is about 0.394 in. The workshop still asks you for millimetres so the SVG width and height attributes stay honest.

A monitor preview is not guaranteed to appear at real-world size. Pixels on a display are not millimetres. Trust the printout and the SVG millimetre attributes, not the on-screen centimetre look of the sheet.

Grid spacing

Spacing presets: 2, 3, 5, 7, 10 mm, plus custom 1–25 mm. Square and coordinate grids use that value on both axes. Dot grids use it as center-to-center pitch. Isometric grids use it as perpendicular distance between parallels in a family. Hexagonal paper uses hexagon side length (the hex control). Triangular paper uses triangle side length. Lined paper uses it as the gap between horizontal rules.

Validation rejects zero, negatives, NaN, Infinity, empty required fields, and trailing garbage. Changing paper size does not silently alter spacing.

Major and minor lines

On square and coordinate paper, major lines may be none, every 5 cells, or every 10 cells. On a 5 mm square grid, every 5 cells is a 25 mm block; every 10 cells is 50 mm. Major color is separate from minor color. Styles without that option—dots, isometric, hex, lined, triangular—do not show a major-line control.

Minor thickness presets are 0.15, 0.25, 0.4, and 0.6 mm. Default 0.25 mm is a compromise: visible on most inkjets, not so heavy that a 2 mm grid turns into a grey field.

Page margins

Default 10 mm on all four sides. Printable width = page width − left − right. Printable height = page height − top − bottom. Letter portrait with 10 mm margins: 195.9 mm by 259.4 mm. A4 portrait with 10 mm margins: 190 mm by 277 mm. If either printable dimension falls below 20 mm, the setting is rejected. Many printers cannot print to the physical edge; the margin is there for that reason, not as decoration.

On-screen dashed guides mark the printable rectangle. They are omitted from SVG, PNG, and print output. Lined paper’s optional vertical margin line is a writing guide inside the printable area (default 20 mm from the left of that area), not a replacement for page margins.

Physical print scale

For the intended grid measurements, use actual-size or 100% scaling in the browser print settings. Printer margins and scaling options can affect the final dimensions. This website cannot override every printer setting. A 5 mm square grid should have approximately 50 mm across ten cells. Hardware tolerances and paper handling can still shift the result slightly. The site does not guarantee exact physical output on every printer.

Step-by-step: printing guide.

SVG dimensions

The canonical file sets width and height in millimetres and a viewBox of 0 0 width height in the same millimetre space. Geometry is clipped to the page. Download SVG produces a file named from validated settings, such as gridline-square-letter-5mm.svg. Open it in a browser: the document size should match the paper you chose. There are no scripts and no linked images inside the file.

PNG resolution

PNG is a raster of that SVG on a white background. Standard is 150 DPI. High Resolution, the default, is 300 DPI. Pixels = inches × DPI. US Letter at 300 DPI is 8.5 × 300 by 11 × 300, about 2550 × 3300 pixels. A4 at 300 DPI is (210 / 25.4) × 300 by (297 / 25.4) × 300, about 2480 × 3508 pixels. If a browser cannot allocate a canvas whose longest edge exceeds the engine’s safety limit, you see an error instead of a blank download. Drop to Standard and retry.

PNG does not include preview chrome, margin overlays, or navigation. Zoom in the workshop does not change PNG pixel size.

Checking a printed grid with a ruler

Pick an interior line, not the sheet edge. Count ten cells. On 5 mm squares, look for 50 mm. On 2 mm squares, look for 20 mm. On 10 mm squares, look for 100 mm. Repeat on the other axis. If one axis matches and the other does not, the print was stretched—often a “fit to page” that ignored aspect ratio, or the wrong paper size in the driver. If both axes are short by the same ratio, the whole page was uniformly scaled; reprint at 100%.

More diagrams: understand grid measurements. Ready configurations: paper templates.

FAQ

Return to how to make printable graph paper or the homepage workshop.