What is LPI?
Also known as: Lines per inch
Lines per inch — the resolution measure for halftone screens. Determines how many dot rows are placed per inch in the screen pattern. Higher LPI = finer detail.
In detail
LPI specifies how dense the halftone dot grid is. Lower LPI (30-50) produces visible dots up close but reproduces well on textured fabrics where mesh count limits detail anyway. Higher LPI (55-85) produces finer detail but requires higher mesh count screens and more careful production control. Textile screen printing typically uses 30-65 LPI; offset paper printing uses 133-175 LPI; high-end magazine printing reaches 200+ LPI. The LPI must be lower than the mesh count of the screen by a factor of roughly 2 to avoid clogging — printing 65 LPI through a 110 mesh screen is the upper limit; printing 65 LPI through 86 mesh produces dot loss. Designers specify LPI based on fabric texture (higher LPI for smooth cotton, lower for textured linen) and print partner mesh capability.
Example
A polyester sport jersey print at 50 LPI through 156 mesh screens — fine enough detail for the gradient sleeve fade, coarse enough that dot gain doesn't muddy the design. Same design printed at 30 LPI through 86 mesh on heavy canvas would show visible dots up close but would survive the canvas weave better.