File facts: a beginners guide to file formats for custom t-shirt designs

The fundamentals of file formats

Creating custom merch has never been easier, but achieving professional, high-quality print results still depends on one crucial detail: using the right file format.

Whether you’re printing a simple company logo on a T-shirt, embroidering caps, or creating a design with bold graphics on the back of a t shirt, your file type directly affects clarity, colour accuracy, and overall finish.

This guide explains the best file format for printing, breaks down vector vs raster, and answers the most common questions printers and designers get asked, especially by first-timers.

Why File Format Matters for Printing

In printing, ultimately the needed file type is determined by the printing technique used. Using the wrong file format can result in blurry edges, pixelation, colour shifts, or poor-quality output, especially at larger sizes.

That’s why designers and printers almost always ask for vector files when printing logos and other simple graphics. However, when your artwork is textured and has many details, raster files are able to convey them with more depth.

Vector vs Raster: What’s the Difference?

Before choosing the best file format for printing, it’s essential to understand the difference between vector files and raster files.

What is a Vector File?

A vector file is a digital image created using mathematical formulas rather than pixels. These mathematical equations define shapes, lines, curves, and colours.

Because of this, vector images are:

• Infinitely scalable (can be resized without losing quality)

• Always crisp, clear, and sharp

• Ideal for logos, illustrations, and branding assets

• Easy to edit without degrading image quality

This is why vector files are essential for professional printing and brand consistency, as a vector logo can be easily converted from the size of a business card to fit the back of a t shirt with no loss in quality.

But remember that, as well as being in one of these file formats, you specifically need to export your file as vector file when one is needed.

What is a Raster File?

A raster image is made up of a fixed grid of coloured pixels. The quality depends on the number of pixels and the resolution.

Raster files:

• Are resolution-dependent

• Can become pixelated or blurry when enlarged

• Are best suited to photographs and detailed images

• Must be at least 300 DPI for printing

Common raster formats include JPEG, PNG, and PSD.

Vector or Raster: Which Is Best for Printing?

For Logos, Text, and Simple Illustrations → Vector Files

Vector files are the gold standard for printing logos and graphics because they:

• Maintain crisp edges at any size

• Ensure precise colour accuracy

• Prevent distortion or pixelation

• Support easy editing and adjustments, as they can be resized infinitely

If a printer, designer, or marketing agency asks for a vector file logo, this is why.

For Photographs and Detailed Artwork → High-Resolution Raster Files

When printing photos or complex artwork, raster files are optimal due to their ability to convey textured images and details with more depth. However, they must be high resolution (high-res).

Minimum requirements:

• 300 DPI

• CMYK colour mode for DTG printing, CMYK or RGB colour mode for DTF printing

Common Vector File Formats

AI (Adobe Illustrator)

• Native vector format

• Best for editing logos and design elements

• Requires professional design software

PDF (Portable Document Format)

• One of the best file formats for printing

• Can preserve vector properties

• Widely accepted across printers and platforms

• Ideal for sharing and document transfer

EPS (Encapsulated PostScript)

• Industry-standard vector format

• Widely used for professional printing

• Excellent for logos and branding

SVG (Scalable Vector Graphics)

• Fully vector-based

• Infinitely scalable

Common Raster File Formats

PSD (Photoshop Document)

• Designed for high-resolution image editing and storage

• Uses lossless compression

• Supports high color depth (8-bit, 16-bit, and 32-bit)

• Allows repeated editing without quality loss

JPEG (JPG)

• Uses lossy compression

• Smaller file size, lower quality

PNG

• Must be saved with a transparent background

• Generally higher quality than JPEG

Summary of File Guidelines for Printing

However, there can be exceptions to these guidelines based on the quantity you are planning to order, the intricacy of the design or photo you want to print, and what kind of products you want.

What If You Don’t Have a Vector File?

If you only have a JPEG or PNG version of your logo, don’t worry.

While at ICON we don’t currently offer full design-from-scratch services, we are always happy to help you get your existing artwork ready for print — most of the time free of charge. For complex designs, an artwork charge of usually £15.00 per design is applied.

Frequently Asked Questions

Is PNG or JPEG better for printing?

Ultimately, the file type required depends on what printing technique is used. For example, for screen printing, AI, EPS, or PDF is required, whereas for DTG printing, other formats like PNG, JPG, AI, and EPS are suitable as well.

Is PDF or JPEG better for print?

PDF is usually the better choice, especially for more simple logos and layouts. Again, the choice depends mostly on the printing method used.

Is a PDF a Vector File?

A PDF can be vector or raster, depending on how it was created; PDFs exported from Illustrator or InDesign often contain vector data, whereas PDFs created from images may be raster-based. A good way to tell is by zooming in closely and looking at the edges of your art: if edges stay sharp → vector, if edges blur → raster.

What is the best vector format for logos?

AI, EPS, SVG, or vector-based PDF.

Is a PNG a Vector File?

No. A PNG is a raster file, not a vector file. Even though PNGs can look sharp on screens and support transparency, they are still made of pixels and can become blurry when enlarged for print.

Can you turn a PNG into a vector?

Yes, it can be recreated as a vector file.

Is a JPG a raster file?

Yes. JPEGs are raster images.

Is JPG and JPEG the same?

Yes, JPG and JPEG are the same file format. The 3-letter abbreviation (.jpg) originated from older Windows operating systems, and modern computers, web browsers, and image editors treat .jpg and .jpeg files identically.

What resolution do I need for printing?

At least 300 DPI for raster images.

Still unsure?

If you have any further questions or need assistance in figuring out which printing technique and therefore file format is optimal for you, we are here to help.

Contact us at sales@iconprinting.com or call +44 (0)207 183 8431. We promise to help you through the process and discuss the possible options, so that you get the best results.