Reference · Printable
Isometric paper
A triangular lattice built from vertical lines and two diagonal families at 30° from horizontal. Sketch a cube on it and the drawing comes out in true isometric projection — measurable, parallel, no vanishing point. Print it free at any triangle size.
The geometry, briefly
Look at a cube along its body diagonal — the line joining two opposite corners — and its three edge directions project onto the page 120° apart. Stand one of them upright and the other two settle at 30° above and below the horizon. That is the whole construction: the grid on the right is those three directions repeated, and every intersection is a point where all three meet exactly.
The practical payoff is measurement. Because nothing converges, one ruler serves all three axes: a 30 mm edge drawn along any grid direction is 30 mm of real length. Add a vanishing point and that stops being true, which is why plumbing schematics, exploded assembly diagrams and isometric game art all stay on this grid rather than moving to perspective.
One cube, three axes at 120° — the projection the grid is built for.
5 mm — general purpose
The commercial pad standard. Fine enough for product sketches, coarse enough to draw freehand without counting.
10 mm — massing & rooms
Larger triangles for furniture layouts, room studies and anything where one triangle should stand for a bigger unit.
¼ inch — US drafting
6.35 mm, the traditional imperial spacing, pairing naturally with Letter-size sheets.
Frequently asked questions
What makes paper "isometric"?
Three families of lines instead of two: vertical lines, plus two diagonal families running 30° above and below horizontal. Their intersections form equilateral triangles, and any cube drawn on that lattice appears in isometric projection — all three visible faces at equal foreshortening, with no vanishing point. It is the reason a hand sketch on this grid reads as three-dimensional without any perspective construction.
Why 30 degrees specifically?
Isometric projection views a cube along its body diagonal, which places the three axes at 120° apart on the page. Two of them land at ±30° from horizontal and the third stays vertical — so a grid at those angles gives you the axes ready-made. Drawings at 30° also scale cleanly: distances along all three axes use the same ruler, unlike dimetric or perspective drawings.
What triangle size should I choose?
5 mm is the general-purpose default and matches most commercial isometric pads. Choose 10 mm for large massing studies and quick furniture or room sketches where each triangle represents a bigger unit, and 3–4 mm for detailed mechanical parts. In inches, ¼ in (6.35 mm) is the traditional US drafting spacing.
Is isometric the same as 3D perspective?
No, and the difference matters when you measure. Isometric drawings have no vanishing point: parallel edges stay parallel forever and a 10 mm edge is 10 mm whether it is at the front or the back of the object. Perspective drawings converge and foreshorten, which looks more natural to the eye but makes the drawing unmeasurable. Engineering, plumbing schematics, and game art favour isometric for exactly that reason.
What is isometric paper used for?
Product and furniture sketching, mechanical part drawings, piping and plumbing isometrics (a formal deliverable in process engineering), architectural massing studies, pixel-art and game-tile design, mathematics teaching around volume and nets, and knitting or beadwork charts on a triangular repeat.
Does the printed grid stay accurate?
Yes, provided you print at 100% / Actual size — the PDF is vector, so a 5 mm triangle measures 5 mm with a ruler. If your print dialog is set to "Fit to page", every triangle shrinks by a few percent and any measured drawing you make on top inherits the error.