Grid Maker online

Drawing a clean grid in a paint app means placing lines one by one. Here the spacing and line weight are uniform from the first line to the last.

The canvas is 1200 × 800 pixels unless you type another width or height between 16 and 8000. Line color starts at a deep red. The square size is fixed at 5 mm at 300 DPI, which is about 59 pixels, and the lines are about 2 pixels wide at 45% opacity. A white margin of 120 pixels runs around every side, and the grid updates as you type.

The lines run all the way to the right and bottom margins, but the last vertical and horizontal lines sit on the last whole 5 mm step, so the final column and row are usually narrower, open-ended squares. On very small sizes, under about 300 pixels, the margins leave little or no room for squares. The background is white rather than transparent, so the PNG will cover anything you place it over.

5mm Graph Paper uses the same 5 mm spacing but outputs a page-sized PDF with heavier lines every second square, made for printing. Perspective Grid draws a one-point perspective guide instead of flat squares. For a grid that cuts a photo into tiles, use Image Splitter.