In short: a print-ready DTF file is 300 DPI at the size it will be printed, has a fully transparent background, has no semi-transparent pixels around the edges, has no lines thinner than about 0.5 to 1 mm, and is RGB. PNG is the safest raster format; SVG, PDF, AI and EPS are best when you have vector artwork.
Why DTF is strict about files
DTF prints a layer of white ink behind the colours, wherever the artwork is not fully transparent. That white layer is what makes DTF vivid on dark shirts, and it is also why DTF is unforgiving: every pixel that is even 5% opaque gets white ink under it. Problems that are invisible on screen become visible on a shirt.
Here is what to check, in the order it usually goes wrong.
1. Resolution: 300 DPI at the final print size
300 DPI at the size you print is the standard every DTF shop asks for. The key words are "at the final print size": DPI is not a property of the file alone, it is pixels divided by inches.
- A 3,000 pixel wide image printed 10 inches wide is 300 DPI.
- The same image printed 15 inches wide is 200 DPI.
- Printed 20 inches wide, it is 150 DPI.
Around 200 to 250 DPI is often acceptable for large back prints viewed from a distance. Below about 150 DPI, most designs look soft or pixelated. Changing the DPI number in Photoshop's "Image size" without adding pixels changes nothing on the print.
If your file is too small, you have three options: print smaller, find the vector original, or upscale. Upscaling made for photos tends to smear flat-colour artwork; see how to upscale artwork for DTF.
2. A transparent background
Anything in the file that is not transparent is printed. That includes:
- A white background. It prints as a white box.
- A "nearly white" or light grey background from a JPG. It prints as a faint grey box.
- A checkerboard pattern that someone flattened into the image. Yes, it prints.
Use a PNG with real transparency. JPG cannot store transparency at all, so a JPG always prints with its background unless it is removed first.
3. No semi-transparent edges (the halo problem)
This is the most common reason a "good" file prints badly. Soft, anti-aliased or feathered edges, drop shadows, glows and AI-generated images all contain pixels that are partly transparent. DTF puts white ink under them, so the design gets a thin white or light outline on dark garments, and the edge can have weak adhesion.
The fix is to "choke" the edges: make every pixel either fully opaque or fully transparent, and pull the white layer slightly inside the colour. We explain it step by step in how to fix white halos in DTF prints.
4. Lines and text that are thick enough
Very thin lines print, but they may crack, lift or wash off. Shops and suppliers do not agree on one minimum; published guidance ranges from about 0.5 mm to 1 mm for lines, and 6 to 8 pt for text, with fine script fonts needing more. Design for a safe size, not the absolute minimum. More in minimum line thickness for DTF.
5. Colour: RGB, not CMYK
Most DTF RIP software expects RGB (sRGB) files and does the conversion to the printer's inks itself. Sending CMYK can make colours shift, because the file gets converted twice. A few shops ask for CMYK, so check with yours, but RGB is the safe default.
- Pure black (0, 0, 0) prints as a deep black.
- Very dark colours close to black can print with white ink under them and look slightly lifted; ask your printer whether they knock out black.
6. File formats
| Format | Use it for | Watch out for |
|---|---|---|
| PNG | Raster artwork, photos, finished designs | Must have transparency, enough pixels |
| SVG | Vector logos and text | Convert text to outlines; embedded images still need resolution |
| Vector or mixed artwork | Fonts embedded or outlined; transparent background | |
| AI / EPS | Vector artwork from Illustrator | Outlines, no hidden background layers |
| JPG | Only when nothing else exists | No transparency, compression artefacts around edges |
| PSD | Layered Photoshop files | Hidden layers and effects; export to PNG first |
A gang sheet builder accepts most of these and converts them; the sheet itself goes to the printer as one 300 DPI PNG.
Print-ready checklist
- 300 DPI at the final print size (at least 150 DPI for anything)
- Transparent background, no white or grey box
- No semi-transparent edges, shadows or glows
- Lines at least 0.5 to 1 mm, text at least 6 to 8 pt
- RGB colour
- Text converted to outlines in vector files
- Design sized for the garment (see the size chart)
Checking a file automatically
You can check all of this by hand in Photoshop, or upload the file to FileFixxr. It reads the artwork at the size you will print it and shows what would go wrong on press. The check is free and needs no account. With a PrintReadySheets plan, the fixes it suggests, from line thickening to edge cleanup and upscaling, are applied for you instead of being sent back to the customer.
Frequently asked questions
What DPI do DTF transfers need?
300 DPI at the final print size. 200 to 250 DPI can work for large prints; below 150 DPI the result usually looks soft.
What is the best file format for DTF printing?
A PNG with a transparent background at 300 DPI for raster designs. For logos and text, a vector file (SVG, PDF, AI or EPS) is even better because it stays sharp at any size.
Can I use a JPG for DTF?
Only if you remove the background first. JPG has no transparency, so the background prints, and its compression leaves noise around edges that DTF picks up.
Should DTF files be RGB or CMYK?
RGB in most cases. The RIP converts to the printer's inks. Ask your printer if they want something else.
Why does my DTF print have a white outline?
The file has semi-transparent pixels around the design, from anti-aliasing, a glow, a shadow or an AI generator. DTF prints white ink under them. Choking the edges fixes it.