Graph Paper Generator

Why printed graph paper is so often the wrong size

CSS has real physical units. A rule written as 5 mm is 5 mm on paper, and an inch is defined as exactly 25.4 mm, so a grid drawn this way is correct before it ever reaches the printer. Every line, dot and circle on this sheet is positioned in millimetres, and the SVG itself declares its width and height in millimetres rather than pixels.

The trouble starts in the print dialogue. Chrome's scale menu opens on Default, which fits the sheet to the printable area rather than printing at full size; Firefox offers fit-to-page-width in the same spot. Either quietly shrinks the page by two to five per cent, turning a 5 mm grid into a 4.8 mm one — invisible until you measure it.

Hardware margins do the rest. Many home printers cannot put ink within about five millimetres of the paper edge, so a sheet with no margin gets scaled to fit what the printer can reach. A margin of 10 mm or more here usually removes the reason to rescale at all.

The check bar, and what to do with it

Leave the check bar on for the first print. It is a 100 mm rule with a tick every 10 mm along the bottom of the sheet. Put a real ruler against it. If it reads 100 mm the grid above is already exact — turn the bar off and print the rest of the pad.

If it reads 97 mm, type 97 into the measured box. Every dimension is multiplied by 100 ÷ 97 before it is drawn, so the next print comes back at the size you asked for. The check bar is scaled too, which makes the fix self-verifying: print again and the bar should now measure a true 100 mm.

One caveat. The correction stretches the artwork, not the sheet, so the blank border ends up a fraction of a millimetre off the margin you typed: the squares are exact, the margin approximate. Corrections beyond five per cent usually mean a setting is wrong, and the page says so.

Picking a pattern

• Square — 5 mm with a heavier line every fifth is the classic exercise-book grid.
• Isometric — three line families at 30°, 90° and 150° forming equilateral triangles. The spacing you type is the triangle side.
• Dot grid — the square lattice with the lines removed, so your own drawing is what shows. Dot size follows line weight.
• Hexagonal — pointy-topped honeycomb sized across the flats, for organic chemistry and for map games.
• Polar — rings at a fixed spacing plus spokes at a fixed angle, for bearings, vectors and the complex plane.
• Semi-log — logarithmic vertical axis against a linear horizontal one. Exponential growth plots as a straight line.
• Log-log — both axes logarithmic, so a power law plots straight and its exponent is the gradient.

Line weight, ink and toner

Weight is set in millimetres, not pixels, so it means the same thing on any printer. Around 0.15 mm is a light guide line, 0.2 to 0.25 mm reads as ordinary graph paper, and past 0.4 mm it competes with what you draw on top. Heavier lines are drawn at double the weight you set.

When spacing approaches line weight the sheet prints as flat tone, so the page warns you if the two come within a factor of four. Coloured ink is offered because pencil reads better over blue or green — but a mono laser dithers those to grey, and a fine dithered line breaks up.

Questions

Will the squares really measure 5 mm on my printer?

At 100 per cent scale, yes — everything is laid out in true millimetres. Since most dialogues do not open at 100 per cent, print once with the check bar, measure it, and if it is out by a millimetre or two type the measured figure in. After that the grid is right for that printer.

Which print settings do I need to change?

Scale to 100 per cent instead of Default or Fit to page width. Headers and footers off. Paper size matching what you chose here. Leave the dialogue's own margins at Default — this page sets the margin itself through an @page rule, and overriding it in the dialogue is what forces a rescale.

Can I download the sheet instead of printing it?

Download SVG gives you a vector file whose width and height are stated in millimetres, so Inkscape, Illustrator, Affinity and most plotter and cutter software open it at true size. Copy SVG puts the same markup on the clipboard. There is no PDF export: the browser's own Save as PDF destination produces a better file than an in-page PDF library would.

Does it work in inches as well as millimetres?

Switch the unit and the spacing, margin and decade boxes convert with it at exactly 25.4 mm to the inch. A quarter-inch grid comes from the inch figure rather than a rounded 6 mm stand-in, and the check bar becomes a four-inch bar. Line weight stays in millimetres, which is how pen widths are quoted.

Where is the sheet generated?

In your browser. A script on the page builds the SVG on your own machine, so the settings you type never leave the device and the tool still works if the connection drops. The advertising slot is a separate matter and will load third-party resources of its own once advertising is enabled. Nothing is saved between visits — reloading returns you to the defaults.

What this page will not do

It draws one sheet at a time: no multi-page pad, no repeating header, no two patterns on one page. Polar and logarithmic sheets are grids rather than charts — no data plotting, no axis titles, no fitted lines.

The logarithmic sheets number the lines inside each decade but do not label the decades, because only you know whether the bottom line is 1, 100 or 0.001. Very fine settings make heavy files, so if the preview stalls, widen the spacing.