, 10mm (1cm) squares: primary school arithmetic, counting activities, and large handwriting. The most forgiving size for young learners.
, 6.35mm (1/4 inch) squares: the standard quad-ruled size in US notebooks and the default for general school maths.
, 5.08mm (1/5 inch) squares: five squares to the inch, the classic engineering pad layout in imperial-measurement work.
, 5mm squares: the metric everyday standard, used across European and Asian exercise books for maths and science notes.
, 2mm squares: detailed plotting and small-scale graphs where you need to read values off the paper precisely.
, 1mm squares, usually with accented lines every 5 and 10: millimetre paper for drafting and laboratory plotting.
, Larger accented grids: any size with every fifth or tenth line drawn heavier, which makes counting squares far faster.