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Halftone LPI vs mesh count

PrintSeps guides · updated October 2026

The line count of your halftone and the thread count of your mesh have to agree, or the dots either fall through the mesh openings or get chopped by the threads. This guide gives the ratio, a table of starting points, and the angle rule that keeps the two from fighting.

The ratio

Divide mesh count by halftone LPI. For dots to resolve cleanly the result should be at least 4, and 4.5 to 5 is safer. A 50 LPI halftone on 230 mesh is a ratio of 4.6: fine. The same 50 LPI on 156 mesh is 3.1, and the small dots will be inconsistent. The ratio is about dot size, not just moiré: at 4 threads per halftone cell, a 10% dot is about the size of one mesh opening, which is the smallest thing that will survive exposure, washout and the squeegee.

Starting points by mesh

Shops running mostly manual presses and plastisol tend to live at 45–55 LPI on 230 mesh. Going finer buys smoother tone only if exposure, film density and registration can keep up; past that, finer just loses highlight dots.

Smallest and largest usable dots

Every mesh has a floor and a ceiling. Highlight dots below about 5–10% drop off the screen during exposure and washout; shadow dots above about 85–90% fill in on press. Separations should be built so the meaningful tones live in between: pull the darkest areas back from 100% so the shadow dot stays open, and don't rely on 3% dots for detail. Finer mesh and better exposure widen the range, but no mesh gives you 1% to 99%.

Dot gain

Ink spreads when it hits fabric. A 50% dot on film typically prints as a 65–75% dot on a shirt; the gain is larger on coarse mesh, soft garments, and manual presses with heavy squeegee pressure. Compensate in the separation by pulling the midtones down, not by printing lighter on press. A sim process plate with no dot gain correction looks right on the monitor and prints dark and blocked.

Screen angle and the mesh

The halftone grid and the mesh grid are two regular patterns laid on top of each other, which is the recipe for moiré. Screen printers avoid the CMYK angle set (0°, 15°, 45°, 75°) because 0° and 45° line up with the threads. The usual choices are 22.5° or 61°, and in simulated process every plate uses the same angle, since the inks are opaque and sit side by side rather than overprinting transparently. If you print true CMYK process on a light shirt, offset all four angles by 7.5° (7.5°, 22.5°, 52.5°, 82.5°) to keep each one away from the mesh.

Dot shape

Elliptical dots are the default for garment printing: they join corner to corner gradually across the midtones instead of all at once at 50%, which hides the tonal jump a round dot makes. Round dots are fine for coarse work; square and line screens are special-purpose.

A worked example

A six-color sim process job on black tees on a manual press: underbase on 156 mesh at 40 LPI (choke 1 pt), colors on 230 mesh at 50 LPI, black line plate on 305 at 55 LPI, highlight white on 230 at 50 LPI, every plate at 22.5°, elliptical dots, midtones pulled about 15% for gain. That's a set of films a shop can register and print without surprises.