The squares measure 5" x 5". The rectangles measure 5" x 6.6"

JRV stencils are durable at 15mil thick. They are thicker than most other stencil lines. The most important way to get a clean stencil line is to use a good quality stencil brush and "offload" almost all of the paint on the brush. Stipple, or pounce up and down on the surface.