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Beginner's handbook

Everything You Need to Know to Prepare the Perfect Print File

By Reading Time: 6 minutes

You’ve set up your store and you’re ready to start earning a profit. But your entire business hinges on this one element – getting the print file just right, so that your design can be displayed in its full glory that your customer will then bask in for the remainder of that garment’s lifetime.

And just when you think you nailed it, an order has come in and it goes to processing, and the unimaginable happens.

Your order’s put on HOLD! *gasp!*

Printing is delayed, and you have to tinker with the design to get the right print file.

I’m here to say you can get it right the first time!

I spoke to Printful’s graphics department to identify the most common errors with print files so that you can avoid them the first time around. These tips focus on print files for our most popular product: DTG-printed t-shirts.

Graphics basics

To get started, here are some general rules of thumb to keep in mind when thinking about print files:

Max. printing area: 12×16 inches and we scale print files down depending on the t-shirt model and size.

DPI: Files have to be a minimum of 150 dpi (digital pixels per inch) to ensure optimal quality. Any lower and the print will be blurry and pixelated.

Do submit these file formats: .png, .psd

Don’t submit these file formats: .ai, .pdf, .eps

Our sublimation shirts have a different set of guidelines, which you can take a look at here. File & image size is the top offender

Another super important thing to keep in mind is the design itself – make sure that your design corresponds to Printful’s Acceptable Content Guidelines. Remember that content that is hateful, illegal, and that violates intellectual property rights may be reviewed and removed at any time.

Top reasons your order is on hold

1. Overall image quality

One of the most common issues are low-quality images, or images that are too small to be qualitatively scaled up. So the best thing you can do right off the bat is submit a large, high-quality print file. This section walks you through what that looks like!

When it comes to size, make sure the image you’re submitting is actual size, and that it reflects how big you actually want it on your garment. All submitted images should be no less than 150 dpi. If your image has fine details, we suggest submitting the image at 300 dpi. And it’s always best to submit a larger print file that we can scale down instead of vice versa.

If we do print out a low-resolution file that’s scaled up, then it will be blurred, stretched, and the edges will be pixelated. Generally not what high-quality online stores should be aiming for.

When you upload a bad file in the mockup generator it’ll look like it’s 150 DPI and then you’ll think it’s fine. But the root of the problem is still that you’re submitting a bad print file. Even 300 dpi does not guarantee a quality print if you use a low-quality file in the first place. If you uploaded a bad quality photo or just typed in a different resolution in Photoshop, then the quality may still be poor.

Tip: To quickly find out if your image is large enough to be printed in a good quality, upload it to the mockup generator and see if you can scale it to the desired size. We don’t recommend scaling the file to a point where resolution drops below 150.

These are the top signs of a poor quality print file:

  • Pixelated edges
  • Blurry image

2. Transparencies 

Another common problem is when print files include semi-transparent pixels/values/elements.

These are not recommended in DTG printing because the white underbase will be showing through those semi-transparencies, creating a very speckled look, which can often look poor quality. We suggest using 100% opaque (solid) colors only.

What it looks like when transparencies are printed

To avoid this result, use half-toning to achieve a similar  “glow” effect. Read more about how to do this here.

3. Backgrounds

Always remove backgrounds!

Even if you’re printing on a white garment and you think it’ll be fine if you leave the white background – don’t. It may cause quality issues.  

If you’re printing a black background on black, then you’ll be left with a greyish rectangle around your design. That’s because these prints on dark garments require a white underbase, and as a result, the printed black will be a lighter shade than the actual garment.

Orders are frequently put on hold because the backgrounds haven’t been completely removed. If any residue at all is left over, it will be visible when the shirt gets printed. The way we test this (and you can, too) is by opening the file in Photoshop, adding a different color background, and duplicating the layer several times to make any residue show up.

Bottom line: we suggest you avoid solid backgrounds entirely (unless it’s an express part of your design).

If you’re printing on a white t-shirt, we suggest removing any white elements in the design. This is because we don’t print white ink on white shirts. If your artwork includes white, it won’t print.

4. Missing or incorrect inside label info

If you’ve decided to print a custom inside label on your shirt, there’s info you’re required by law to add:

  • Garment’s country of origin
  • Size
  • Fabric info

These details are different for each shirt model, so make sure you have the right info before you submit your print files!

Also remember that the print area is 3×3, and the minimum font size is 6 pts. You can download print file guidelines for inside labels here.

One layer of ink is best for tiny graphics like inside labels. This is because the white underbase can sometime show around the letters. For the cleanest results possible, we recommend submitting white only graphics for colored and dark shirts, so graphics can be printed with one layer of ink (white) only. For white shirts any color will work, except white.

A word to the wise – dark inks can be see-through on lighter garments. This is something to keep in mind if you’re not into that look!

Bonus tips!

Make sure the colors on your screen match the printed colors

The colors you see on your screen are not always what you see when the garment has been printed. It’s a good idea to order our RGB swatches onto the garments you want to print to see how they’ll show up in real life.

As I mentioned earlier in this post, you should submit your print files in .png or .psd. You should avoid PDF files, Illustrator files, and other vector formats because don’t always convert properly (they end up printing hidden layers, or there can be missing fonts). Vector files are typically created within the CMYK color space while we require RGB. Also, CMYK files can’t be exported as .png’s. You can work within CMYK, but before saving your file, change it to RGB. This is actually recommended because the RGB range is wider and you can go crazy with neons, magentas etc. However, printers will never be able to reproduce these colors, as they use the CMYK color gamut.

Pro tip: get in touch with our design services if you need help with color correcting.

Choose the right garments for the best possible outcome

Your designs will look different depending on the fabric blend you print on. For example, ink is more spread out and looks more faded on sweatshirts since it’s a thicker fabric.

The best way to find out how your design will look on the garment you want to print on is to order samples! You can get a sample for 20% off and free shipping, so this is great if you want to test out a product before offering it on your store.

Tip: When printing on totes, don’t design with white. Because of how the white underbase reacts with the fabric, the ink tends to scrape off, so we don’t print white ink on Natural totes (black totes are fine).  

Conclusion

Keeping an eye out for these most common mistakes is a must – it’ll speed up the time your order goes from submission to shipping, and it’ll lead to happier customers (aka more moolah for you!). If there’s anything to remember from this post is – check the guidelines, use high quality graphics, accurately size your files, and voila – you’re set to start making that uber cool independent online store that just happens to be raking in the cash.

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  1. Martha J Sayre

    I have tried over and over to figure out what size image to upload, but despite attempting to use 150 dpi, the site still says my “image is too small” and that the dpi is “bad.” It suggests changing the size of the image on the outline but I am unable to figure out how to accomplish that. No mater what size image I try, it does not work for shirts or leggings. Why does the site not at least give a suggestion? Is 12 inches by 12 inches at 300 dpi too big? That wouldn’t seem to upload at all, yet when I make the design smaller, it doesn’t work. Very frustrating. Any help you can provide would be appreciated.

    1. Giedrė Kronberga

      Hi Martha! The DPI requirements for print files varies for each product. For example, 150 DPI is totally ok for DTG and sublimation products, while smaller items like mugs and phone cases require print files to be at a higher resolution because prints are small and often detailed. So make sure you double-check DPI requirements for the product you picked.

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