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Printful 101

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. Chris

    Hi Nora,

    I am confused about file sizes when imprint areas change depending upon size. If I am making a graphic for a women’s shirt, should I make the file 10×12 or 12×16? I am guessing that you guys can scale up or down and that I wouldn’t need two different files.

    Appreciate your help!

  2. yopi

    nice post, very useful. I’m starting to make small money from t-shirt. First because i can’t always get the t-shirt i want, so i make my own. my question is: how to make gradation edges on DTG? (I use black Gildan softstyle mostly) example: Skull with fire background, the skull need the white underbase, but how to make the fire background edges soft without white underbase, meanwhile, if I don’t use the underbase, the fire dissapear. thank you (forgive my english)

  3. InkMasters

    Wonderful information. In addition always save your files in print-ready, and do not use layers and reduce everything to the background layer .Perfect print-file is very useful to increase your work productivity. I really appreciate your post because reading your post i have collected much useful information.

  4. Véronique Poliquin

    Hi there,

    I find it very “weird” that you guys are telling us to send psd at 150 dpi and when I did, the print came out wrong so I uploaded a eps and everything went well even though you say to not summit eps files… I AM CONFUSED !!!

    Thanks

  5. Kiko

    Hi – Is there an increase in print quality if i submit art @ 300 dpi or do all submitted files get automatically downgraded to 150?

    1. Nora Inveiss

      Hey Kiko!

      When you submit an order or sync a product, your print file will save in whatever DPI you used. If you create a print file with the mockup generator, it automatically shrinks down to 150 DPI.

      If your graphic has a lot of fine details, you might want to go with a higher DPI. Otherwise, there isn’t a difference in quality between the 150 and 300.

  6. Geoff

    I make my own designs on Adobe illustrator and being I’m not that big into digital design yet I don’t know exactly how to make a 12 by 16 with 150 plus dpi. I would love to use you guys But I’m not sure how to get the DPI up any higher Because at The quality I set it at which is decent upon creation it looks good on everything I put it on now, But your print file system doesn’t seem to like it.

    Any ideas to make the quality as best as possible on Adobe illustrator . Should I make it with a different frame size like 1800 by 1920 or something or is there something I can do in the program itself to make it better quality on the edges .

    1. Nora Inveiss

      Hey Geoff! Here’s how:

      1. File –> New –> on the right hand side type in 12 (width) & 16 (height) –> create
      2. Paste in (or create) your design at the intended size within the artboard
      3. File –> export as –> select PNG and (important!) check ‘’use artboards’’ http://prntscr.com/hkbuht –> export
      4. select resolution 150dpi or 300dpi from the dropdown menu http://prntscr.com/hkbuzq
      5. Enable ‘transparent background’’
      6. Click OK

      Hope this helps!

  7. macbook technical support

    While doing the work perfectly you need to the concepts very clearly where you will find out the way to make the things in a perfect manner which will be helpful for the person to run the best part so printing is not the way you should know the particular things which you will get to know through the experts.

  8. Ricoh printer

    Printful’s graphics
    The graphic makes a nice photo and converting into a file is a very difficult job. In this, a simple tutorial is given which is very helpful for the users

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