What LPI should I use for screen printing?
Start from your mesh count: ScreenPrinting.com’s halftone guide gives the rule of thumb mesh count ÷ 5 = LPI, or mesh count ÷ 4 for more detail when your screens can hold it (source, checked 16 October 2026). Their example is a 160 mesh screen: 32 LPI by the first rule, 40 LPI by the second.
The tool starts at 45 LPI, which is what the ÷ 5 rule gives for a mesh of about 225. Treat it as a first guess, not a recommendation for your press. Print a test, then move the LPI down if the small dots close up or wash out, and up if the dots are visible from where people will see the shirt.
For DTF there is no mesh to match. Pick an LPI where the smallest dots you keep are still big enough for your printer, and use Clear below to drop the rest. The DTF halftone page has dot sizes in millimetres.
What screen angle should I pick?
22.5° is the usual starting point for single-colour work on mesh. The same ScreenPrinting.com guide recommends it, and warns that rows of dots at 0° or 90° line up with the threads of the mesh and won’t print, and that 45° loses detail.
Angles matter less for DTF and other film or digital transfers, because there is no woven mesh for the dots to clash with. Line dots at 0° or 90° give a clean horizontal or vertical line pattern if that is the look you want.
How many pixels does each dot get?
The distance from one dot to the next, in pixels, is the dpi divided by the LPI. A cell of that size can show about as many tone steps as it has pixels, so a coarse screen at a high dpi shows smoother gradients than a fine screen at a low one.
| LPI | Dot spacing | Pixels per dot at 300 dpi | Pixels per dot at 600 dpi |
|---|---|---|---|
| 25 | 1.02 mm | 12 × 12 (144) | 24 × 24 (576) |
| 35 | 0.73 mm | 8.6 × 8.6 (73) | 17.1 × 17.1 (294) |
| 45 | 0.56 mm | 6.7 × 6.7 (44) | 13.3 × 13.3 (178) |
| 55 | 0.46 mm | 5.5 × 5.5 (30) | 10.9 × 10.9 (119) |
| 65 | 0.39 mm | 4.6 × 4.6 (21) | 9.2 × 9.2 (85) |
Below about 4 pixels per dot the shapes stop looking round or square, and the tool tells you so. If you need a fine screen, choose 600 dpi.
What each setting does
| Setting | What it changes |
|---|---|
| Shading or Transparency | Shading: dark areas become dots in one ink. Transparency: semi-transparent pixels become dots in their own colours, for DTF |
| Dots on | Dark areas (black ink on a light shirt) or light areas (light ink, such as white, on a dark shirt) |
| Ink | The colour of the dots in Shading mode |
| Dot shape | Round, Ellipse (dots join along one direction first), Square, or Line (parallel lines that get thicker) |
| Lines per inch | How many rows of dots per inch of print |
| Screen angle | How far the rows are turned, 0° to 90° |
| Print size | The width in inches or centimetres, and 300 or 600 dpi; the height follows the image |
| Clear below, Solid above | Tones that print nothing, and tones that print solid |
| Knock out the shirt colour | Removes colours near the shirt colour before the dots are made; colours a bit further away fade into dots |
| Smooth dot edges | Adds partly transparent pixels around each dot. Off by default |
The tool works the way a print RIP screens an image: each pixel is compared with a threshold from a repeating dot pattern, and it is inked if the image is darker than the threshold there. The thresholds are ranked so a tone covers the same share of each cell whatever the dot shape. In our tests on flat grey fills, the share of inked pixels stayed within 2.5 percentage points of the grey’s darkness for every dot shape (tested 16 October 2026). The same image and settings always give the same pixels.
What the halftone generator does not do
- It makes one screen, not a set of CMYK or spot colour separations.
- It does not vectorise the dots. The PNG is pixels at the dpi you choose; pick the print width before you download rather than scaling the PNG afterwards, which would blur or distort the dots.
- It does not add registration marks, a film border or a mirror image.
- It reads PNG, JPG, WebP, GIF, BMP and AVIF, not PSD, SVG or PDF. A Procreate file can be turned into a PNG first with the converter.
Doing it in Photoshop or GIMP instead
In Photoshop, convert the image to Grayscale, then choose Image > Mode > Bitmap with the Halftone Screen method and set the frequency, angle and shape. The result is a flat bitmap with a white background, so you then select the black and copy it to a transparent layer if you need a PNG. GIMP has Filters > Distorts > Newsprint. This page does the same job on any computer, gives a transparent PNG at the print size straight away, and adds the transparency mode that DTF files need.