How to enlarge a drawing using a grid: sizes and worked example

To enlarge a drawing, multiply every length by the same number. Scale factor equals target width divided by reference width. Check the height with that factor too. A 15 × 20 cm reference fits a 30 × 40 cm drawing at 2× scale: 30 ÷ 15 = 2 and 40 ÷ 20 = 2. This is twice the width and height, and four times the area.

A 30 × 30 cm canvas does not have the same shape as that reference. Stretching it to fill would require 2× horizontally and 1.5× vertically, distorting the subject. Instead, keep a 22.5 × 30 cm drawing with side margins, or crop the reference to a square before gridding. Make this choice before transferring any detail.

Divide the reference into six columns and eight rows. Each reference square is 2.5 cm, because 15 ÷ 6 = 2.5 and 20 ÷ 8 = 2.5. On the destination, keep those same six columns and eight rows, but use 5 cm squares. Check that 6 × 5 = 30 and 8 × 5 = 40 before drawing the grid.

Make pencil ticks every 5 cm on the top and bottom edges and every 5 cm on the left and right. Connect opposite ticks with a ruler. Measure the outer rectangle and check that the first and last squares agree; a small repeated ruler error can accumulate across the whole drawing.

Transfer points by their position within a cell. A line halfway across the source square belongs halfway across the enlarged square. Its absolute distance changes from 1.25 cm to 2.5 cm, but its relative position does not. Connect major contours and check the whole silhouette before working on texture.

Open your photo in the drawing grid tool, select A4 and choose Columns with a value of 6. Enable Target surface, choose cm, and enter width 30 and height 40. The reference grid is 186 × 248 mm, with six columns and eight rows of 31 mm squares. The destination cells are 50 mm, filling the requested 300 × 400 mm drawing rectangle.

The on-paper reference in this setup is not the original 15 × 20 cm example: ArtGrid fits it to printable A4 space. That changes the reference-to-drawing scale to approximately 1.613×, while preserving the six-by-eight correspondence. Use the displayed reference and drawing cell sizes rather than measuring a browser preview, which changes with screen zoom.

Export the single-sheet PDF if you will rule the enlarged grid by hand. For a full-size paper template, use the multi-page printing tool and check its page-count preview. Tiled exports above four sheets currently show an unlock or coming-soon control; do not assume every target size is available for immediate download.

Fit the drawing inside the target without changing its proportions. With a six-by-eight grid on a 40 × 40 cm canvas, a 5 cm cell size gives a 30 × 40 cm drawing. Centre it with 5 cm margins on the left and right. Extending the artwork into those margins is a new composition decision, not a scaling operation.

In ArtGrid, Columns or Rows mode retains the derived grid counts when the target changes. Cell size mode with a target instead derives counts from the requested destination square size. Recheck the counts after changing modes so an old hand-ruled drawing does not get paired with a different reference layout.

Print at Actual Size or 100% and measure the PDF calibration bar. Fit-to-page can shrink a correct file, and borderless settings can enlarge it. If you are using tiled sheets, use the assembly diagram to place them, verify a shared boundary and follow the PDF's instructions before taping.

For canvas or a wall, mark the drawing rectangle and a few major landmarks lightly first. Check their spacing from the edges at normal viewing distance. This short proof exposes a wrong crop or scale while the marks are easy to move. Keep the clean reference for shading once the enlarged outline is established.