What is the best file type to save my design for printing?

JPG

AI

PNG

It depends on your design.

Most of the time a JPG file is best. Especially if your design is a square or rectangle.
yoga JPG on shirt


If your design needs a transparent background like the shirt below then you need a PNG file.
png on shirt

PNG files can save with a transparent background which is perfect for printing on fabric. PNG files with transparency won’t show a background. You can see in the image below the background is transparent as shown by the black and white check pattern.
png in photoshop

If this image was saved as a JPG instead of PNG it would print with a white square.
png as jpg on shirt

FAQs

What is an AI file?

Adobe Illustrator (AI) is a software application by Adobe for making vector files. We need to export AI files to JPG or PNG before we print. It might be best for you to export the file yourself, especially if you have special fonts, we may not have on our computer. Or just save text as curves to avoid font problems.
ai file in adobe illustrator