DTF print file requirements: PNG, 300 DPI and a transparent background

A DTF print file is a PNG with a transparent background at 300 DPI at the size it will be printed: a design printed 28 cm wide needs 3307 pixels across. Large half-transparent areas, such as soft shadows, glows and fades, are the usual trouble, because DTF lays white ink under the printed colours and cannot print a pixel half see-through. Lines and text must be thick enough to survive the transfer, commonly 0.5 to 1 mm depending on the printer, and the file should hold only the design: no background and no garment colour.

This guide explains each requirement, what goes wrong without it, how to check a file before it goes to the printer, and how a WooCommerce shop gets files like this from customers who design their own products online. For how DTF compares with DTG and screen printing, see DTF vs DTG vs screen printing.

Which file format does DTF printing need?

PNG is the format DTF printers and transfer suppliers ask for most, because it keeps a transparent background without losing detail. Many also accept vector files, which scale to any size; the printing software turns them into pixels when it prints.

Format	Transparent background	For DTF
PNG	Yes	The usual choice
SVG, PDF, AI, EPS (vector)	Yes	Good when your printer accepts it, with text converted to outlines
JPEG	No	Avoid: its background is printed as a box of ink

A JPEG cannot be transparent, so whatever surrounds the design, usually white, is printed with it: on a black shirt, a white rectangle.

What resolution does a DTF file need?

300 DPI at the printed size. DPI is the number of pixels in each inch of the print, so the pixels a file needs follow from the size you print it: the width in inches times 300, or the width in centimetres divided by 2.54 times 300.

Printed width	Pixels across at 300 DPI
7.5 cm	886
3 in	900
25 cm	2953
28 cm	3307
11 in	3300
30 cm	3543
12 in	3600

Below about 150 DPI at the printed size, softness is visible at a normal viewing distance; small text and thin lines suffer first. Enlarging a small image in an editor adds pixels but no detail: a 1000-pixel logo stretched to 3300 pixels prints as soft as the original would at that size. The DPI number stored in the file means nothing on its own; what counts is the number of pixels against the printed size. Print-ready t-shirt files explains this in more detail, and print areas and print sizes lists common sizes per product.

Set the canvas to the printed size at 300 DPI before you design, rather than designing small and scaling up at the end.

Why does the background have to be transparent?

DTF prints the colours onto film with a layer of white ink behind them, so the design stays bright on any colour of fabric. Everything in the file that is not transparent is printed, with white behind it:

• A white background prints as a white rectangle, not as “no background”.
• The garment’s colour as a background prints as a patch of ink that never quite matches the fabric, and makes the transfer larger and stiffer than it needs to be.
• White inside the design prints white. Where the shirt should show through, the file must be transparent, not white.

Half-transparent areas: shadows, glows and fades

A pixel that is half see-through has no clear answer on a DTF printer. Depending on the printing software, a large half-transparent area can print as a solid block, as a pale haze over the shirt, or not at all. Soft drop shadows, glows, feathered edges and photos that fade into the background are the usual causes; the edge of a photo cut out with a soft brush often has a ring of them. The thin smoothing along the edges of text and shapes is normal and is not what this is about.

To fix them:

• Make the pixels of shadows, glows and fades fully opaque or fully transparent.
• Turn a fade or a soft shadow into halftone dots, which print as solid dots of different sizes.
• Cut out photos with a clean edge, or give them a thin solid outline.

Thin lines, small text and fine detail

A transfer has to hold together when its film is peeled off and through every wash afterwards. Hairlines, tiny text and small isolated dots are the first parts to break or lift. Printers commonly ask for lines of at least 0.5 to 1 mm and gaps of a similar size; ask yours for its own minimum. Thin script fonts and outlined text at small sizes are the usual problem, so check them at their printed size.

RGB or CMYK?

Many DTF printers and suppliers ask for RGB PNG files and let their printing software convert the colours to its inks; some ask for CMYK. Send what your printer asks for. Either way, a screen gives off light while ink on fabric reflects it, so bright on-screen colours such as neon greens, blues and pinks print duller. When a colour has to match, ask for a test print. RGB or CMYK for t-shirt printing? sets out what each method asks for and which colours print furthest from the screen.

How to check a DTF file before printing

1. Check the pixels against the printed size. Divide the file’s width in pixels by the printed width in inches: 300 or more prints sharp, below about 150 looks soft. In centimetres, a sharp print needs about 118 pixels for every centimetre.
2. Look for a background. Open the file over a dark background in an image editor. Anything you see that is not the design, such as a white box or a coloured patch, will be printed.
3. Find half-transparent areas. Zoom in on shadows, glows, fades and the edges of cut-out photos. Make those pixels fully opaque or fully transparent, or turn the fade into halftone dots.
4. Measure the thinnest line and the smallest text. View the design at its printed size and compare its thinnest line and smallest letter with your printer’s minimum, commonly 0.5 to 1 mm.
5. Save it as a PNG with transparency. Export a PNG with its transparent background kept, at the printed size, in the colour mode your printer asks for, and name it with the order number and the side.

The DTF image checker makes the first three checks for you in your browser, with the file’s format and the DPI value written in it: choose the file, enter the width it prints at, and it says what passes and what to fix. It cannot measure your printer’s minimum line, so check the thinnest lines by eye.

Getting DTF-ready files from customers who design online

When customers design their own products in your shop, most of these rules can be built in, instead of checked by hand on every order:

• Every design is made at the size it will print, because each side of the product has a print area with its real size.
• The customer is warned before ordering when an image is too small for the size they placed it at, instead of you finding out at the printer.
• The file is made by software, so it always has a transparent background and exactly the right number of pixels.

PrintBlob does this in WooCommerce. With PrintBlob Pro, each printed side of an order becomes a transparent PNG at 300 DPI at exactly its print area’s size (a 28 × 36 cm print area becomes 3307 × 4252 pixels), made when the customer adds the design to the cart and kept with the order together with the customer’s original images. Beside it come a vector PDF and an SVG of the same size, with typed text converted to outlines, for printers that accept vector files. The print queue lists every designed item still to print, with each order’s files in one ZIP. The free plugin keeps every order’s design and preview and warns customers below 150 DPI, so PrintBlob Pro also makes the files of orders placed before you add it. PrintBlob Pro is $69 a year or $99 once (limited-time offer until 31 December 2026) (Free and Pro compared).

Two things no designer can check for you: half-transparent areas inside a customer’s own logo, such as a soft shadow, and hairlines in it. Look at uploaded logos before you print: the order keeps the customer’s original image, so you can fix it at full quality.

Questions about DTF print files