A common rule of thumb is to use a mesh count four to five times your halftone line frequency: 180 to 225 mesh for a 45 LPI halftone, or about 46 to 57 LPI on a 230 mesh screen. Underbase, a Windows separation app for screen printers, builds that into its film output: Suggest ruling from mesh picks a ruling from the mesh count you enter at a 22.5 degree angle, dot gain compensation thins the plate for the gain you measure, and the film header records the mesh and ruling for each plate.
Picking the line count is the step that decides whether dots hold or fall through the mesh. This guide gives a chart, explains why the rule exists, and shows where each setting lives.
Set halftone ruling from your mesh count and print film that says what it was made for.
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What is the rule for mesh count and LPI?
The help center at ScreenPrinting.com puts it simply in What mesh count should I use for halftones?: choose a mesh count that is 4 to 5 times your halftone line frequency. Work backward by dividing the mesh by 4 or 5 to find the highest LPI a screen can reliably hold.
The reason is physical. A halftone dot needs to sit on enough mesh threads to stay anchored in the stencil. If the line count is too high for the mesh, the smallest highlight dots fall between threads and either wash out during exposure or print unevenly.
What LPI goes with which mesh?
| Mesh count (threads per inch) | LPI at mesh divided by 5 | LPI at mesh divided by 4 |
|---|---|---|
| 110 | 22 | 27.5 |
| 156 | 31 | 39 |
| 180 | 36 | 45 |
| 200 | 40 | 50 |
| 230 | 46 | 57.5 |
| 280 | 56 | 70 |
| 305 | 61 | 76 |
The 4 to 5 times rule and the 230 mesh example come from ScreenPrinting.com’s help center, checked on 17 October 2026. The other rows are the same arithmetic. Treat the lower LPI in each row as the safe choice and the higher as what a well tuned shop can hold.
The same article adds that a 230 mesh is the safer choice for a 45 LPI halftone if you are newer to printing halftones or want more insurance, and that exposure quality, screen tension and overall process all affect how much detail a screen can reproduce.
Why does the rule leave a range?
The range between 4 and 5 times exists because shops differ. The same help article says a high-quality exposure unit and a well dialed-in process can work at the lower end of the mesh range, while the upper end gives more margin. Thread diameter, emulsion thickness, exposure time and screen tension all move the limit. If you are unsure, burn a test screen with a tonal ramp at two rulings and print both. The ruling whose smallest dots survive washout and print cleanly is your shop’s real number for that mesh.
What else has to be right on a halftone plate?
Line count is only one setting. Each halftone plate also needs:
- An angle that avoids moiré. Halftone dots and mesh threads are both regular patterns, and the wrong angle between them shows as a visible interference pattern. Underbase’s ruling suggestion uses 22.5 degrees; test on your own press if you see a pattern.
- Dot gain compensation. Mid-tones print darker on press than on film. Measure your gain on a test print and thin the plate by that much.
- The right film resolution. The printer or RIP has to be able to draw clean dots at your line count. Higher output resolution gives smoother dot shapes.
- Labels. The film should record the mesh, ruling and angle so the screen room burns it on the right screen.
Our film positive checklist goes through every check before exposure.
Try the halftone and mesh settings on one of your own jobs during the 15-day free trial.
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How do I set ruling, angle and dot gain in Underbase?
Underbase separates customer art into spot or index plates, builds a choked white underbase, and writes true-size film. Halftone settings are per plate:
- Open the art. PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF and Illustrator (.ai) files open; vectors are rasterized at 300 dpi at their true size.
- Pick the plate. In the Inks and plates list, select the ink you want to screen and turn on Halftone this plate. The underbase can be halftoned too, with Halftone the underbase.
- Enter the mesh. Type the mesh count. Suggest ruling from mesh sets the ruling from that mesh count at 22.5 degrees and turns the halftone on, and the Mesh field reminds you that halftones want at least four times the line count in mesh.
- Adjust if needed. Set the Screen ruling anywhere from 10 to 120 lpi, the Screen angle from 0 to 90 degrees, and a tint if the whole plate should print lighter.
- Compensate for gain. Enter your measured gain in Dot gain compensation, from 0 to 50 percent, and the plate’s halftone is thinned to match.
- Check the dots. Output dots shows the plate at the output resolution, so you can see the actual dot pattern before film.
- Generate. Choose Generate underbase pack (Ctrl+G). Film TIFFs are 1-bit CCITT Group 4 at 600, 720, 1200 or 1440 dpi, and the true-size film PDF has registration marks, center ticks, and a header with the job, plate, ink, screening, offset, mesh and dpi.
How does the plate budget fit in?
Every halftone plate is still a screen. Underbase’s plate budget counts the underbase and every printing ink against the screens your press holds, and holds generation until the job fits. If a halftone design needs more screens than you have, Merge inks to fit the budget merges the closest inks in one click. See screen printing color separation software for the full workflow.
When is a different tool the better choice?
- Simulated process on a lot of photographic work. Underbase handles spot and index separations for limited-color jobs. Tools built specifically for simulated process separation suit that style of art better.
- Your RIP already screens. If your RIP software applies halftones and you send it unscreened art, you may prefer to let the RIP set ruling. Underbase writes unscreened 8-bit channel TIFFs for that case, alongside the 1-bit film.
- Mac shops. Underbase runs on Windows 11 version 24H2 or later, x64.
Frequently asked questions
What mesh should I use for 55 LPI?
By the 4 to 5 times rule, 220 to 275 mesh. A 230 mesh holds about 46 to 57 LPI per the ScreenPrinting.com guidance, so 55 LPI sits near the top of its range.
Does Underbase pick the mesh for me?
No. You enter the mesh you plan to use, and Suggest ruling from mesh picks a ruling for it.
Can I set a different ruling for each plate?
Yes. Ruling, angle and tint are set per plate, including the underbase.
What output resolution should I use for halftone film?
Underbase writes film at 600, 720, 1200 or 1440 dpi. Use the highest resolution your film printer or RIP handles well, and check Output dots before generating.
Does the film show the mesh?
Yes. Each sheet’s header names the job, plate number, ink, screening, offset, mesh and dpi.
Try Underbase
Underbase is a one-time purchase in the Microsoft Store, with a 15-day free trial. Open a halftone job, enter your mesh, and check the output dots before you burn a screen. For more, see halftone film positives, screen printing separation terms, or the Underbase product page.
Make the dots on film match the screen they will be burned on.
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Last updated 17 October 2026. Published by Automata Labs, a software company in Canada.