First up, Lines Per Inch (LPI). This represents the number of lines intersecting in every square inch. If a design has big dots, there will be a lower number of lines and a lower LPI. Small dots equals a higher number of lines across and a higher LPI.
So how do you determine the optimal LPI based on the mesh count you’re using? It’s a simple equation. Say you want to use a screen with a 160 mesh count. Take that number and divide it by 5. So for a 160 mesh count screen, the ideal LPI would be 32.
If you’re looking to push for greater detail and have a dialed-in darkroom, try a higher LPI by dividing the mesh count number by 4 instead of 5. Using a 160 mesh screen, you’d get 40 LPI. The dot size will be smaller and it will be harder to keep all that detail.
Pro Tip: To use Adobe® Photoshop and try to keep as much detail in a photograph, remember that LPI and resolution are linked. This means you won’t be able to achieve more detail on the shirt than you would see in the image at 2.5 times the LPI. If you want to keep 300 DPI (Dots Per Inch) in the photo, divide that by 2.5 to get 120 LPI.