Graph paper comes in many grid sizes, and the right one depends on what you are drawing. Here is a quick guide to the common choices.
1/4 inch squares (6.35 mm)
The default in US schools. Four squares make an inch, so a heavier line every four squares marks inch blocks. It is comfortable for handwriting numbers inside squares, for plotting graphs and for scale drawings in imperial units.
1 cm squares
The metric equivalent for classrooms. Large enough for young children to write in and for bar charts with clear labels. A heavier line every 5 squares gives 5 cm blocks.
5 mm squares
A popular all-round metric grid for notes, diagrams and maths. Two squares make a centimetre, so a heavier line every 2 squares draws centimetre blocks. Close in size to 1/4 inch, which makes it easy to switch.
1/8 inch and 2 mm squares
Fine grids for engineering-style sketches, circuit layouts and detailed charts. They hold more detail but are harder to write inside, so use them for lines and shapes rather than numbers.
Millimeter paper
A 1 mm grid with heavier lines at every 5 or 10 mm. It is used for technical drawing, plotting precise data and measuring from scans. Print it on a good printer at actual size and in a darker colour so the very fine lines stay visible.
Grid sizes for crafts and pixel art
Cross-stitch, knitting and pixel-art charts work best on 5 mm or 1/4 inch grids with a heavier line every 5 or 10 squares, which helps you count stitches or pixels. For crochet or beadwork you may need non-square grids, so keep an eye out for a separate generator.
Choosing heavier lines
A heavier line every few squares gives your eye an anchor. Common patterns are every 4 squares on 1/4 inch paper, every 5 on 1 cm and every 10 on millimeter paper. For clean coordinate graphs, centre the axes and number them at each heavier line.
Start from a preset in the graph paper generator: 1/4 inch, 1 cm, 5 mm or millimeter.