Free Rectangular Grid Maker

The arithmetic is simple enough to do in your head once you know to do it. Cells are square when the ratio of columns to rows equals the ratio of the canvas's width to its height.

So the default here — 8 columns by 10 rows — gives square cells on a canvas whose width is 0.8 of its height. That is 4:5, the classic portrait format and the shape of a great many photographs shot in portrait orientation.

On other shapes the same counts give other cells. On a square canvas 8 × 10 gives cells 1.25 times as wide as tall. On a 3:2 landscape frame they come out at 1.875:1 — nearly twice as wide as tall. On 16:9, 2.22:1.

Those numbers matter the moment the reference and the working surface are different shapes. Copy from a 3:2 photograph onto a 4:5 canvas using the same 8 × 10 counts on both, and the reference cells are 1.875:1 while the canvas cells are 1:1. The drawing comes out 87.5% wider than it should be.

Which is a large enough distortion to be obvious in the finished work and entirely invisible while you are doing it, because inside each cell the copy is faithful.

The lock-square control removes the problem by force. It sets both cell dimensions to whichever is smaller, so the cells are square regardless of the counts and the canvas shape. The copy is then guaranteed undistorted.

The cost is that the grid stops filling the canvas. On a 1200 × 800 frame with 8 columns and 10 rows, the cells would be 150 wide and 80 tall; locked square they are 80 × 80, so the grid covers 640 pixels of the 1200 available and leaves 560 unused across the width.

That is not a bug and it is the correct behaviour — a square grid at those counts genuinely does not fit that frame — but it surprises people, and it is better to know before than to discover it mid-setup.

The usual right answer is to choose counts that match the canvas rather than to lock. On a 3:2 canvas, 12 × 8 gives square cells. On 16:9, 16 × 9 does. On A4 portrait, the ratio is 1:√2, which no whole-number pair matches exactly — 10 × 14 is within 1%, which is close enough that no eye will find it.

There is a genuine case for unequal cells, and it is worth stating so the whole thing does not read as a warning. If the reference and the surface are different shapes and you have decided to accept the distortion — a deliberate stretch, a stylised elongation, a design that has to fill a specific space — then unequal cells give you a controlled, uniform transformation rather than a guessed one.

Sign painters and muralists use this deliberately. A design drawn at one proportion and installed at another can be gridded across, and the resulting stretch is exact and repeatable rather than eyeballed.

The history of the method goes back at least to the Egyptians, whose figure canons were laid out on grids of specified proportion — the standing figure occupying eighteen squares from foot to hairline in the classic canon, revised to twenty-one in the Late Period. Those are proportional systems as much as transfer grids.

The rectangular grid overlay page follows that history, beside the rest of the drawing-grid category. Alberti describes a version in De pictura in 1435, and Dürer's woodcuts of the 1520s show the apparatus: a gridded frame between artist and subject, a matching grid on the paper. Those images are the reason the method is often called Dürer's grid, though he documented it rather than invented it.

The method's reputation has been damaged by an argument it is not part of. Using a grid is sometimes treated as a shortcut that bypasses observation, but the grid does not draw anything — it constrains where marks go, and every judgement inside a cell is still yours. The reason it survives in teaching is that it isolates the shape-judging skill from the proportion-judging one so they can be learned separately.

The cell labels are what make it teachable. A1-style labels — letters across, numbers down — let a group of people refer to the same square, which is the difference between a demonstration and a set of individual struggles.

The label size control matters more than it looks. At 40% the labels are unobtrusive on a dense grid; at 220% they are readable across a room. For a printed worksheet you want small; for a wall demonstration you want large.

The half grid is the standard escalation. When a passage — a face, a hand, a piece of lettering — needs more resolution than the main cells give, halving each cell gives four times the detail without changing any coordinate. Cell C4 is still C4; it just has four quadrants now.

Drawing it at 45% opacity rather than full is what keeps the two levels distinguishable. A half grid at the same weight as the main grid is just a finer grid, and you lose the ability to work at the coarse level when you want to.

The margin control insets the whole grid, which is what a drawing sheet with a border needs and what every printed worksheet has. It also gives you somewhere to write, which sounds trivial and is the difference between a usable teaching sheet and one people write on top of the drawing.

For a grid specified in millimetres rather than in counts the custom grid maker takes over, and the proportion calculator works out the scale factor between the two surfaces. The highlight picks out one cell at 2.2 times the line weight. Over a long transfer it is a place-keeper; in a lesson it is a pointer; in a commission conversation it is how you and a client agree which part of the reference you are discussing.

The grid draws over your own image rather than exporting a fixed template because the counts have to be chosen against a specific reference. How many cells a subject needs is a question about the subject's complexity, and it cannot be answered on a blank sheet.

The export sizes itself from the paper format and the DPI you choose rather than from your screen, so a worksheet printed at A4 and 600 DPI has genuinely fine lines. SVG keeps every line editable, and the labels come through as text.

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.