DTF transfer file requirements: a checklist before you print

DTF (direct to film) has become one of the most popular ways to put designs on shirts, hoodies, bags and hats. It handles full colour, works on dark and light fabrics, and doesn't need a separate screen for every colour.

It's also unforgiving about files. The printer prints exactly what's in your PNG, including the parts you can't see on screen. Here's what to check before you send anything.

Every DTF printer has its own spec sheet. Use this as a general checklist, and always follow your printer's exact requirements where they differ.

1. Size the file to the actual print size

Set up your artwork at the size it will be printed, in inches or centimetres, not "as big as possible."

Typical sizes, as a rough guide:

• Left chest: about 3.5 to 4 inches wide
• Adult full front: about 10 to 12 inches wide
• Youth front: about 8 to 9 inches wide
• Sleeve: about 3 inches wide
• Hat front: about 4 to 5 inches wide

If you're printing on a gang sheet, each design still needs to be at its real print size on the sheet.

2. Resolution: 300 DPI at that size

The common requirement is 300 DPI (pixels per inch) at the final print size.

To check it, multiply the print width in inches by 300. That's how many pixels wide your file needs to be.

• A 4-inch left-chest print needs about 1,200 pixels wide.
• A 12-inch full-front print needs about 3,600 pixels wide.

A small image enlarged to that pixel count doesn't count. Enlarging adds pixels but not detail, and the print will show soft edges. If your source is small, it needs to be rebuilt, not stretched.

3. Genuine transparency (no background box)

DTF prints every pixel in the file that isn't fully transparent. If your PNG has a white or coloured background, you'll get a white or coloured rectangle on the shirt.

Check for these common problems:

• A fake transparent background. Some downloaded images show a grey and white checkerboard that's actually part of the picture. Open the file on a dark background; if you still see the checkerboard, it isn't transparent.
• Leftover specks. Stray pixels around the design, often from a quick background removal, print as tiny dots.
• A halo. A thin light outline around the artwork, left over from the old background, shows up badly on dark garments.

4. Watch out for semi-transparent pixels

This is the one people miss. Soft shadows, glows, faded edges and low-opacity effects are made of partly transparent pixels. Many DTF processes lay a white underbase beneath the colour, and partial transparency can print as a faint, muddy or blotchy area instead of a smooth fade.

Safer options:

• Make effects fully opaque, or remove them.
• Replace soft fades with a halftone (a pattern of solid dots that creates the look of a gradient).
• Ask your printer how they handle opacity. Some RIP software deals with it well, some doesn't.

5. Minimum line thickness and small detail

Very thin lines and tiny text can print weakly or peel away after washing, because there's too little adhesive to hold them.

A common guideline is to keep lines at least about 0.5 mm (roughly 1.5 points) thick at the final print size, and small text at around 8 points or more, especially thin fonts. Distressed and grunge textures with lots of tiny isolated specks are also risky.

Zoom to 100% at actual print size and ask: would this survive a wash?

6. Colour

• RGB is usually fine for DTF. Most printers' software converts it. Check with your printer if you're unsure.
• Very dark colours on dark shirts can almost disappear. Consider a lighter outline or a slightly brighter shade.
• Brand colours: if exact matching matters, tell your printer the HEX or Pantone values and ask for a test.
• Neon and metallic effects rarely reproduce as they look on screen.

7. File format

• PNG with transparency is the standard for DTF.
• Some printers also accept PDF or TIFF; check first.
• JPG doesn't support transparency, so it always gives you a background box.
• If you have a vector file (SVG, AI, EPS), you're in the best possible position: it can be exported as a perfect PNG at any size.

The pre-print checklist

Before you upload, run through this:

1. Is the file at the real print size?
2. Is it about 300 pixels per inch at that size?
3. Is the background genuinely transparent, with no stray specks?
4. Are there soft shadows, glows or faded edges that could print badly?
5. Are all lines and text thick enough to survive washing?
6. Will the colours show up on the garment colour you've chosen?
7. Is it a PNG (or the format your printer asked for)?

If any answer is "no" or "not sure," fix it before ordering. Reprinting a batch of shirts costs far more than fixing a file.

Common reasons DTF files get rejected

• Background box or fake checkerboard transparency
• Image too small, enlarged from a web graphic
• JPG compression artefacts around the edges
• Hairline strokes and tiny text
• Semi-transparent shadows and glows
• Artwork cropped too tightly, with parts cut off at the edge

If your design fails one of these checks, send it to us. We rebuild it at the right size and resolution, clean up the transparency and edges, and prepare it for DTF or whichever print method you're using. You'll see the exact price before you pay.