How to halftone artwork for DTF and screen printing

Why halftone a DTF print?

A DTF transfer is ink plus a layer of adhesive powder, pressed onto the shirt. Over a big solid area that is a heavy, warm patch that can crack as the shirt stretches. Breaking fills and fades into dots lets the fabric through: the print is lighter and softer, uses less ink and adhesive, and a fade can melt into the shirt instead of stopping at a hard edge. It is also the look: the “vintage” print is mostly a coarse halftone on a dark shirt.

Screen printing needs halftones for a different reason. A screen either passes ink or it does not, so any tone that is not solid has to become dots, and the mesh limits how small those dots can be.

What size should the halftone be?

The size it will print. This is the step people skip. A halftone is a grid of dots with a set spacing: made for a 10-inch print at 35 lines per inch, it has 350 dots across. Enlarge the file to 14 inches and every dot is 40% bigger; shrink it and they close up. So set the printed width before anything else, and make a new halftone for each size you sell.

The artwork itself needs enough pixels for that size: roughly 300 for every printed inch is the usual rule of thumb. The print size checker tells you whether a file holds up.

How many lines per inch?

Lines per inch (lpi) is how many rows of dots fit in an inch. Lower is coarser: bigger dots, more visible, softer and more forgiving on fabric. Higher is finer: more detail, but small dots fill in on cloth and can fall off DTF film.

For shirts, starting points usually sit somewhere between 25 and 55 lpi, and paper-printing figures (85 and up) are the wrong range for fabric. For screen printing, the mesh count caps it; your screen supplier will have a rule for the ratio. The honest answer is the one on your own press: halftone a small test at two or three line counts and print them side by side.

What angle and dot shape?

• Angle. A grid at 0° lines up with the weave of the fabric and with the mesh of a screen, and the two patterns interfere (moiré). An angle such as 22.5° avoids most of that.
• Round dots are the default, and they hold their shape best.
• Elliptical dots join into chains in the mid-tones, which gives smoother mid-tone transitions.
• Lines are a style: engraved and retro looks.

Which parts of the picture become dots?

It depends on the shirt. On a dark garment, the light parts of the design print and the dark parts drop out, so black areas become shirt. On a light garment it is the other way round. And for a transparent PNG with soft edges, you can let only the artwork's transparency decide, so fades at the edges become dots and the rest prints solid. The generator's preview puts the result on a black, navy, red, grey or white shirt colour, because a halftone that looks right on white can look nothing like it on black.

What goes wrong?

• Dots too small to hold. Tiny highlight dots fall off film or close up on a screen. Drop the smallest tones (“drop tones below”) so a fade ends cleanly.
• Flat, grey-looking prints. Most photos crowd their tones into the middle, so every dot comes out mid-sized. Raise the contrast before screening.
• A leftover background. A white box around the design prints as a white box on a dark shirt. Remove it first with the background remover, and use the transparent PNG checker to be sure.
• Resizing afterwards, for the reason above.

Sources

• Line-count and ratio figures here are rules of thumb, labelled as such; the tool labels them the same way. Your press, ink, film and fabric decide the real numbers.
• Search demand for “halftone generator for DTF” and “color separation for screen printing free” read from Google autocomplete, 21 September 2026.

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