Draws a screentone at true printed size on your monitor, from the line count (LPI), density, and angle you choose. It exists so you can see how a screentone will actually read once it is printed, before you commit to it in Clip Studio Paint.

What this tool does

Give it a paper size, print resolution, lines per inch (LPI), density, angle, and dot shape, and it draws a screentone matching those settings at true (1:1) scale. Dot spacing and dot diameter are shown in both millimeters and pixels, alongside the coverage actually measured from the pixels drawn, so you can compare it against your intended density. Four test patterns — flat tone, gradient, overlay, and a line-art edge test — each answer a different question about how the tone will behave. It can also work out the effective line count when a screentone applied on a larger source page is printed smaller (a "reduced-print conversion").

Where it fits in your workflow

Sweeping the angle offset between two overlaid screentones to see whether moiré appears
Using the test patterns to find the density at which dots blow out or clog, and to check whether thin lines get buried under a screentone

How to use it

Complete the actual-size display calibration near the bottom of the settings panel by matching the on-screen band to a physical ruler at 100mm, then save it. Skipping this step leaves the preview at an approximate scale.
Set the paper size, orientation, and print resolution to match your actual artwork.
Enter the line count (LPI), density, angle, and dot shape.
Switch between the test patterns to match what you want to check: flat tone, gradient, overlay, or the line-art edge test.
Look at the preview from roughly the distance you would view a printed page, then read the dot spacing, dot diameter, and measured coverage in the numbers below it.

What each setting means

Print resolution: The DPI of your artwork. It determines how many pixels the screentone's dot spacing occupies on the source page. Monochrome manga pages commonly use 600dpi.
Line count (LPI): Lines per inch — how many rows of screentone dots are packed into an inch. A higher number means finer dots. Doujinshi black-and-white pages typically fall around 55–70 LPI.
Density: The percentage of the page the screentone dots cover. Past 50%, the polarity flips from printing black dots to punching white holes out of a solid fill, and the on-screen readout switches from dot diameter to a white-gap diameter to match.
Angle: The tilt of the dot grid. 45° is the angle where the dot pattern is least noticeable to the eye, and it is a reasonable default unless you are specifically testing an overlay.
Test pattern: Flat tone fills the whole area at one density; gradient sweeps density from 0% on the left to 100% on the right; overlay layers two screens at an angle offset; the line-art edge test applies a screentone over lines of different widths next to a solid fill.
Overlay angle: Only shown for the overlay pattern — the angle offset applied to the second screen. At 0° it matches a single screen exactly, which makes it a useful baseline for comparison.
Actual-size calibration: Matches 100mm on screen to 100mm in the real world. The saved value is shared with the screen ruler tool.
Reduced-print conversion: Choosing a source size and a print size calculates how much finer the applied screentone becomes (the effective line count) once it is printed smaller. It does not change what the preview shows.

Reading the results and bringing them into Clip Studio Paint

Dot spacing is shown both in millimeters and in pixels on the source page. The smaller the pixel value, the finer the dots are relative to your artwork's resolution — a warning sign that the resolution may be too low for the line count you chose.
Measured coverage is the share of drawn pixels that actually carry ink. If it drifts far from your density setting, the on-screen scale is probably too coarse for the line count to render accurately.
The moiré period is the spacing of the visible ripple pattern that appears when two screens are overlaid. A larger value means a more visible, larger-scale ripple.
In Clip Studio Paint, entering the same line count, density, angle, and dot shape into a tone layer's screen settings reproduces what you see here — match your source resolution to the print resolution you set on this page as well.

How the numbers are calculated

Dot spacing in millimeters is 25.4 ÷ LPI, and its pixel equivalent on the source page is print resolution ÷ LPI. Dot diameter is derived by solving for the radius whose area matches the coverage within one cell: for a circle, radius = spacing × √(coverage ÷ π); for a square, spacing × √coverage ÷ 2; for a diamond, spacing × √(coverage ÷ 2). Past 50% density the polarity flips, and the punched-out area is computed from 1 − coverage instead. The moiré period comes from overlaying two screens of the same line count at an angle difference θ, using dot spacing ÷ (2 × sin(θ ÷ 2)) for the spatial-frequency difference between them. Because the dot grid is square, θ is folded into the 0–90° range and the smaller equivalent angle is used. The screen-to-real conversion defaults to CSS 96dpi and switches to your saved calibration once one exists. The effective line count is the line count divided by the reduction ratio (print width ÷ source width) — printing a B4 (257mm) page's screentone at B5 (182mm) turns a 60-line tone into roughly 84.7 lines.

Accuracy and what this tool does not cover

How accurate the true-size display is depends entirely on whether you completed the actual-size calibration. Without it, the preview falls back to an approximation based on CSS 96dpi, which will not match your monitor's real pixel density. Changing your browser or OS display scaling will also throw off a saved calibration.

In the line-art edge test, any line thinner than 1 screen pixel is still drawn at 1px, so the thinnest few lines will look heavier here than they will print.
Overlay only handles two screens. Three or more overlapping screens, and features like Clip Studio Paint's tone-scraping or gradient screentones, are outside its scope.
It does not reproduce the actual halftone screening a print shop uses (such as FM screening) or the reproduction characteristics of specific output devices. If you need to check an actual image file against print requirements, use Print Preflight instead.

How your data is handled

The screentone rendering and the coverage measurement both run entirely in your browser — the numbers you enter are never uploaded anywhere. Your tone settings and screen calibration are saved to your browser's localStorage and restored automatically the next time you open the page. You can clear the calibration at any time from the "Clear calibration" control on screen.

Frequently asked questions

Do I always need to run the calibration?

You need it to see anything at true size. Without it the preview still renders, but at an approximation based on CSS 96dpi that can be off by roughly 20% on some monitors.

I raised the density to 70% and the dot diameter got smaller. Is that a bug?

No — past 50% the polarity flips to punching white holes out of a solid fill, so the readout switches to a "white-gap diameter." The gap shrinking as density rises further is the correct behavior.

Which angle offset avoids moiré entirely?

A 0° offset overlays the two screens exactly, matching a single screen with no ripple. Any other offset produces some visible moiré, and you can check its spacing in the moiré period readout.

Why doesn't the preview show the whole page?

When the pixel count needed to draw the full page at true size exceeds an internal limit, the preview crops to the center of the page instead. Shrinking the render would blur the dots and defeat the purpose of a true-size evaluation.

What happens once the effective line count goes over 100?

Moiré and clogging risk rises sharply past that point. Consider lowering the line count, or increasing your source resolution before printing at a reduced size.