Free Tartan Grid Generator

In weaving, that arrangement has a name: the sett. It is the sequence of colours and thread counts that defines a tartan, and because the same sequence is used in both warp and weft, the cloth produces the characteristic squares where each colour crosses itself and blended rectangles where two colours cross.

A real sett is symmetric. It runs out from a pivot point, reflects, and repeats — which is why an authentic tartan has mirror symmetry through certain lines and why the pattern looks the same approached from either direction.

This overlay does not do that, and the distinction is worth being clear about. The band positions here come from an even division with a deterministic wobble applied — a sine displacement of up to 1.8% of the dimension, which shifts each band off its even position by a different, repeatable amount.

To anyone who knows the weave, the result reads as an irregular sett and is not one. It gives you the visual character of tartan — uneven bands with a repeating weight pattern — without reproducing any historical sett, and it has no mirror symmetry. For layout and composition work that is exactly what is wanted. For reproducing a specific clan tartan it is not the tool.

The weight pattern is where the structure lives. Every third line is stroked at 1.6 times the base width and the others at 0.8 — a two-to-one ratio. That regular emphasis over irregular spacing is what makes the pattern read as a system rather than as noise.

There is a detail in that emphasis worth noticing. The heavy verticals fall on indices 0, 3 and 6; the heavy horizontals fall on 1, 4 and 7. They are offset by one, which means the crossings of two heavy lines do not form a regular lattice.

That is deliberate. If both families put their heavy lines at the same indices, the heavy crossings would line up into an obvious sub-grid and the pattern would resolve into a plain grid with decoration. Offsetting them keeps the eye from finding that sub-grid, which is a large part of why woven patterns feel woven.

Contrast controls both the weights and the fill strength together, and it does so multiplicatively — at 20% the heavy lines are barely heavier than the light ones and the fills are almost invisible, so the whole pattern flattens toward an even grid. At 100% the hierarchy is at full strength.

That coupling is useful because the two would otherwise need balancing by hand. A pattern with strong fills and weak lines looks unresolved; so does the reverse. Tying them to one control keeps them in proportion.

The tartan grid overlay page covers both traditions, beside the rest of the architecture grid overlays. The other tradition that uses this grid is architecture, and it arrived independently. A tartan grid in planning is one where wide bands alternate with narrow ones, the wide bands carrying the served space and the narrow ones carrying structure, services and circulation.

Louis Kahn's distinction between served and servant space is the clearest statement of the idea, and the Richards Medical Research Laboratories in Philadelphia — completed in 1960 — is its most literal demonstration: laboratory floors served by separate towers carrying stairs, ducts and extract.

The planning advantage is real. Putting services in a dedicated narrow band means they can be reached without disturbing the served space, and it means a building's servicing can be replaced on a different cycle from its structure. Both matter enormously over a building's life.

The same pattern turns up in laboratory and hospital planning as standard practice, in office buildings where a service band runs behind a column line, and in housing where wet rooms are stacked into a narrow zone. In each case the narrow band is doing the difficult work and the wide band gets the light.

For graphic layout, an uneven grid is a way of building rhythm into a page structurally rather than by placement. Alternating wide and narrow columns produces a page where the reader's eye has somewhere to rest, which an evenly divided page does not.

That is most useful in editorial work where one column carries running text and its neighbour carries captions, marginal notes or images. Making those columns different widths states the difference in role before anything is read.

For an even grid the rectangular grid tool is the tool, and for the structural version the structural grid generator. For textile and craft work, the overlay is a design aid rather than a reproduction tool. It gives you a band structure you can colour, and the density control sets how many bands you are working with. Reproducing an existing tartan needs the actual thread counts, which are published for registered setts.

Laying it over a photograph of woven cloth is a reasonable way to read the rhythm of a sample — how many bands, roughly what proportions — even though it will not give you the exact counts. For a designer working from a photograph rather than a sample, that is often enough.

The band positions are fully deterministic: the same density always produces the same positions, and the sine phase differs between the two directions by a fixed amount. So a pattern you set up today reproduces exactly tomorrow, which matters if the overlay is part of a workflow rather than a one-off.

A moiré caution applies here as it does to any fine grid over a photograph. Uneven bands over a woven or printed texture at a similar scale will beat against it. Changing the density by one usually clears it.

The grid draws over your own image rather than exporting a fixed template because the alignment is the decision. Where the wide bands fall relative to your subject is what makes the pattern work or not, and that cannot be judged on a blank sheet.

The export sizes itself from the paper format and the DPI you choose rather than from your screen. SVG keeps both line weights and the fills, so the hierarchy survives into a vector application.

Everything runs in your browser. Images you load are never uploaded, because there is no server for them to reach. The drawing, the transform and the export all happen on your own machine.