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Everything You Need to Know to Prepare the Perfect Print File (Remastered)

By on August 25th, 2020 Reading Time: 9 minutes

The success of your online store heavily relies on the quality of your products, and the quality of your products relies on the print files you create. The better the quality of your print files and designs, the better the overall quality of your products.

Putting in the work means there’ll be less of a risk of your order being delayed due to your design not meeting Printful requirements. Remember that it’s not just about the order: at that end of every delayed order is a customer who’s likely to become upset by having to wait for the product they’re so excited about.

The golden rule behind nailing your Printful print files is—follow the guidelines created by our in-house experts. To explain to you Printful’s make-or-break print file requirements in greater detail, I asked Printful’s Graphics Team for tips that can help you on your way to the perfect print file.

Print file terminology

Let’s lay the foundation here and get into some terminology. It’ll help you get a better grasp of the rest of this blog and Printful’s print file guidelines.

Print size is the actual size of the image as it’ll come out printed on the product. It’s measured in inches or centimeters.

Image file size is measured in bytes. It tells you how much space the image takes up on a disk or drive. For example, the maximum file size of an image you can upload on Printful’s Mockup Generator is 200 MB.

A pixel is a unit of measurement for digital images you see on a screen.

Pixel dimensions express the total number of pixels along a digital image’s width (vertical) and height (horizontal).

Resolution expresses the density of pixels or dots in an image. For digital images, resolution is expressed in PPI—pixels per inch. For printed images, resolution is expressed in DPI—dots per inch.

DPI (dots per inch) is a printing term. Digital devices display images in pixels, and printers print images in dots. DPI is calculated using your digital image’s pixel dimensions and digital image size.

The higher the DPI = the more the dots = the sharper the print.
The lower the DPI = the fewer the dots = the blurrier the print.

To help you visualize the relation between dimensions and resolution, look at the 3 penguins below. The images have the same dimensions (width and height), but they have different resolutions (DPI).

So, which penguin looks the best?

printful-DPI-differences
DPI makes a difference

Unless you’re an advocate of the lo-fi look, you’ll agree the best-looking penguin is the 150 DPI one on the far right. And this is also the penguin that will look the best printed.

Terminology is out of the way. Now back to Printful print files.

Guidelines for Printful print files

For the best results, always check the Printful guidelines and print file templates in the File guidelines tab under each product. That way, you don’t have to worry about the right file formats and DPIs—we’ve got it all figured out for you!

printful-file-guidelines
The File guidelines tab is your friend

A good way of creating designs for print files with the right dimensions and resolution is by using Printful print file templates, especially for all-over print (AOP) and embroidery products. For embroidery, the templates will help you figure how thick your design elements would be, and for AOP, the templates will give you a better understanding of your design size and placement. 

If you’re just getting started with creating digital designs, remember that the built-in tools in Printful’s Mockup Generator (Clipart, Text Tool, Quick Design, etc.) are a fail-proof way to make good print files because our team made them with quality in mind.

Some more good news: the Mockup Generator, where you’ll upload your design and create your print file, will also give you warnings when your image isn’t suitable for printing.

Onto the make-or-break guidelines. 

  • Accepted print file formats: PNG, JPEG.
  • Accepted embroidery file formats: EPS, PNG (JPG accepted, but not recommended: design elements in images of this format always have a background which can make the design look bad, and JPG also unnecessarily increases the embroidery stitch count, making it easy to go beyond the limit).
  • Maximum size of the print area: depends on the product you choose (e.g. the standard print area for t-shirts is 12″ × 16″, but for 11 oz. mugs—9″ × 3.5″).
  • Print file resolution (DPI): again, depends on the product, but should be at least 150 DPI, and no higher than 300—going beyond 300 DPI won’t improve the print quality, just increase file size.

    • Print files for smaller items, like mugs or personalized phone cases, need a DPI higher than 150 because those prints are small and often detailed. We recommend submitting designs for these products with a DPI of 300.
  • Color profile: the final version of your print file should be saved in the sRGB color profile sRGB IEC61966-2.1. You can set the color profile in the image editing software you’re using.  

    • Why sRGB and not CMYK?  

      sRGB has a wider, more vibrant color range (aka gamut) compared to CMYK.

      Our DTG printers work with an upgraded CMYK color space where we’ve added more ink colors, allowing us to achieve print colors that normally fall outside of the CMYK color range. The closest color space to our upgraded CMYK is the sRGB IEC61966-2.1 and that’s why we recommend it for print files.

      Read also: Color Matching Guide for Print-on-Demand Products
  • Acceptable content: your design has to follow Printful’s Acceptable Content Guidelines. If your design is hateful, illegal, or violates any intellectual property rights, our team may block it. You’ll still see the file in your order or File library, but you’ll receive a warning about your design being blocked and we won’t print it.

Read also: Can I Print That? Copyright and Trademark 101

5 Printful print file mistakes and how to fix them

Now that you have an idea of what it takes to create a perfect print file, let’s look at some reasons that can cause your designs to come out in low quality and how to get past them.

1. You resized a low-quality image lowering its DPI even more

As a coffee fanatic, you wanted to create a t-shirt with a moka pot. You found a copyright-free design and uploaded it to the Mockup Generator.

Turns out the 335 × 410 px royalty-free image looks tiny in the 12″ × 16″ t-shirt print area. You decide to enlarge the image right there in the Mockup Generator.

As the image dimensions grow, the number of dots per inch shrinks. The DPI registers as 60—well below Printful’s recommended range of 150–300. What can you do?

bad-quality-print-file-example
Low quality image (left), the same image enlarged (right)

Four options here:

A) You find a new, high-quality image of a moka pot, one that’s 150–300 DPI from the get-go

B) You settle for a smaller image than you wanted 

C) You turn your low-quality image into a vector  

D) You use the image adjusted by Printful’s Smart Image Tool

Option A is self-explanatory, so let’s go into options B, C, and D.

B. You settle for a smaller image than you wanted

In the Mockup Generator, you reduce the dimensions of the image using the blue corners. The dots of the image DPI come closer together, forming a smaller, yet crisper-looking moka pot. You admit it’s not ideal, but accept that it’ll do for what you had in mind.

print-file-mockup-generator
A bit sad, but might work as a pocket print!

C. You turn your low-quality image into a vector

If you have the time or the experience, you can recreate your low-quality moka pot as a vector, using a vector editing program (Illustrator, Inkscape, Affinity Designer, etc.) or an online convertor.  Another option is to get in touch with Printful’s Graphic Design Services for a helping hand.  

Vectors are graphics made of points, lines, curves, and shapes that are based on math formulas. They’re cool because you can resize them as you want without losing any quality. In the design software mentioned, you can use the image trace or pen tools to convert your low-quality graphic into a vector.

Once you have your vector, resize the image as needed for your design and export it as a PNG file. At this point, your vector file has become a raster image. Now, you can upload it to the Mockup Generator and continue designing.

If you want to use stock vectors or other stock images for your designs, double-check that the content is not copyrighted and the image size and DPI are equal to or higher than what Printful recommends.

D. You use the image adjusted with Printful’s Smart Image Tool

First, though, what’s the Smart Image Tool and how does it work?

It works with the help of Artificial Intelligence (AI). The AI we’re using has studied more than 10,000 images to predict how image “information” (number of dots) behaves depending on the changes in image size.

If you want to enlarge an image with a DPI of 38–74, Printful’s Smart Image Tool can make the image size two times bigger than the original without losing any quality. 

In the case of the 60 DPI moka pot: 

  • The Smart Image Tool analyzes the image to see what information can be added to meet Printful’s minimum print requirements   
  • The tool adds the missing information, so that the ”Average” 60 DPI image becomes a 120 DPI “Adjusted” version
  • The adjusted moka pot is still below the recommended 150 DPI, but it meets Printful’s minimum print quality recommendations, and you can add the adjusted design to your store anyway
The Smart Image Tool in action

Remember that if your product design doesn’t meet the absolute minimum print requirements, the Mockup Generator won’t allow you to proceed.

After the minimum requirements are met, though, the quality of your design is in your hands. That’s why we strongly suggest not to try your luck, follow Printful’s guidelines, and choose quality!

2. You made a DTG design with a background that shouldn’t be there

Avoid adding a background color unless it’s a part of your design—this is especially important for the apparel designs you want printed using the direct-to-garment (DTG) technique.

Why? The printer will print all the colors it sees in the design. For the printer, a black background on a black garment does not equal transparent. 

So if you create a DTG design with a black background on a black garment, be aware that it’ll leave a grayish rectangle around your design. And it’ll be gray because prints on all non-white garments require a white underbase to help the colors stand out.

If you want the gray rectangle, that’s cool. But if you don’t, remove the background! 

If you’re not sure if your design has a solid background, open the file in Photoshop, GIMP, or similar image editing software. If the background is transparent, you’ll see the standard white-and-gray checkered background.

white-vs-transparent-background
Design with a white background (left), design without a background (right)

3. You went crazy with transparency where you should’ve kept cool

Transparency as a design element works best for all-over print (AOP) and some other products, but might not look good on DTG. 

The way transparent elements will come out in DTG depends on: 

  • How the design was created (e.g. you used feather brushes, semi-transparent layers, or similar effects, unaware that they’re a kind of transparency) 
  • The transparency level of the elements (100% transparent or semi-transparent) 
  • The color of the garment they’re printed on = if the garment needs white underbase

    • White garments = no white underbase, transparencies will print out fine
    • Non-white, light-colored garments = white underbase will be difficult to notice, but might shine through semi-transparent areas 
    • Dark-colored garments = white underbase might be visible as small white speckles in semi-transparent areas 

Bottom line: keep the white underbase in mind when creating a DTG design, and consider whether or not a semi-transparent effect is what you want. Some designers like the effect of the white underbase showing through, so it’s a matter of taste!

printful-print-file-dtg
Here, the white underbase peeking through is a design decision

For AOP (sweatpants, leggings, etc.) and sublimation (mugs, towels, etc.) products, transparent elements are OK to use because these printing techniques don’t call for white underbase. For AOP, though, you still may want to fill in the entire print area with solid shapes or colors as much as you can to avoid any blank white fabric showing. Unless, again, it’s a part of your design!

This bean bag design is a good example of how to fill the entire surface of an AOP product

Important note on phone cases: The components of your phone case designs should be at 0% or 100% transparency. We don’t recommend semi-transparencies because the final result will end up patchy.

If semi-transparencies are your thing, our Graphics Team recommends using the halftone effect instead. Halftone can be used on any kind of product, regardless of the printing process.

4. You didn’t remove your background properly

Sometimes a design looks fuzzy and low-quality not because of poor DPI, but because the design is left with fuzzy edges from the background not having been removed properly. 

To avoid the fuzz, in your image editing software, duplicate your final design with the transparent background multiple times. The little bits you missed will become more visible and you’ll be able to easily remove those unsightly edges.

Here’s what you might see after duplicating those layers:

print-file-dtg-edges
The yellow arrows point to the fuzzy edges that need to be removed

5. You chose the wrong product for your print

Every product has a different texture and feel when printed.

That’s why, when choosing products for your designs, think about the print placement and design elements, and whether your vision will work for this product. The rule of thumb is, patterns look good as all-over prints, photographs work well as posters, and typography designs are perfect for DTG and embroidery products.

If you’re selling apparel, remember that your designs will also look slightly different depending on the fabrics and fabric blends you print on.

For example, ink is more spread out and looks more faded on sweatshirts than t-shirts since sweatshirts are made from a thicker fabric. And due to the looser weave and combination of fabrics in tri-blends, DTG prints on tri-blend garments will have a vintage feel—the fabric of the garment will peep through the ink (watch out for tips like these in our product descriptions!). 

For some, that faded or vintage feel will be just what the doctor ordered, for others, the print won’t look as imagined and will be perceived as poor quality. 

Read also: Guide to Cotton, Polyester, and Blended Fabrics

On your way to a perfect print file

If there’s one thing to remember from this blog post—stick to our print file guidelines. Knowing the terminology and Printful specs is a must if you want your orders to reach your customers without hiccups. 

If you need help creating, editing, or formatting your print files, get in touch with Printful’s Graphic Design Services.

Ready to start designing? Head to Printful’s Mockup Generator and have a go! To make it more fun, check out this batch of typography designs that you can use on Printful products— download below. 

This article was originally published in November 2017; it has since been updated.

Download free typography designs

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A language lover constantly on the hunt for all things brilliant in life, from polished writing and sparkling conversation to bright ideas and shiny things.
  1. Scott Larsen

    “To avoid this result, use half-toning to achieve the same “glow” effect.”

    You don’t draw any distinction between types of transparency: 100% clear, no ink goes on at all, vs somewhat clear as in that fade in your glow effect… The first is okay, the second is not.

    What “Line screen” should this halftone shoot for? It’s probably worth describing for people how exactly to create a halftone… and note that a halftone is very fine detail so 300dpi is a minimum resolution. If I were doing a halftone I would probably submit the art at 600 just to help keep the round dots round…

    1. Adam

      When creating your halftone: First off, I don’t work for these guys. I own my own graphics studio and silk screen shop. I do not use any post-script software printers or printing profiles. So I make all my separations individually.

      In Photoshop, after you’ve isolated the part of the image that you want to create halftoned (and of course it and the rest of your spot colors have been put together and scaled to the correct size for output), you want to take that isolated image; bring it into a new file; convert to grayscale (still at 300dpi) and then create your bitmap. You’ll see the first prompt in “Color Halftone” is dpi input and output. It will already recognize your 300dpi image and ask for you to enter the output resolution. I use 720dpi.

      From there, you set your LPI and frequency. There are many forums out there for the math you’d want to implement here for ideal results on an ideal screen mesh. Once bitmapping is complete. Convert back to grayscale; use the Magic Eraser tool (tolerance around 11 w/ Anti-ALias checked) on the white from the BG imagery. Zoom in closely and you’ll notice it lightened all the edges of your halftone dots. Duplicate the layer and merge. Problem solved and you now have a high-res workable , halftone file that can be printed as a composite print.

  2. Rana

    Does this go for posters also? I get why Illustrator files are bad for T-shirt printing but they’re the best for paper printing as far as I know. Can you please clarify? I’ve spent weeks preparing my print files in AI and really hope I can use them and not have to redo them in another format. Thanks!

    1. Julia Gifford

      Hi Rana,

      Yes, this is ESPECIALLY true for posters. We’ve had damaged poster cases because of hidden Illustrator layers, that end up getting printed out. To avoid that potential issue, we suggest .png for the most consistently qualitative results.

      1. Rana

        Bummer. Ok thanks for the clarification!

        Side note – are there any plans to add a bulk delete feature for print files? Deleting them one by one is so time consuming and tedious.

          1. Moni

            Question 1 : I wanna do a design for hoddie. What will be the size of the transparent file.?
            Question 2 : I’ll make a design for sleeves also. Please tell me the size of sleeves…

          2. Edward Zarins

            Hey Moni,

            You can check the file guidelines from the product page (under the “file guidelines” tab).

    2. Joey O

      You can easily save files as jpg and png from your ai file if you’re using adobe illustrator’s “save for web” in the file menu. This is pretty basic.

  3. Scotch

    Agree with Rana – need a bulk delete feature for print files. Taking this a step further, a bulk edit feature. For example, used 12×16 template for XS men’s instead of 10×12. I’d like to edit that print file for only the XS products (20 designs x 7 colors), but doesn’t seem possible, other than manually editing every XS product.

  4. Kristin

    You have a rather funny typo in the short paragraph just above the skulls. Otherwise, extremely helpful. Thank you!

  5. marcus

    I`m just starting out with you guys and back “Scotch”, would want selective bulk editing as well.

      1. Jacki

        Hi Nora, I’ve a follow-up question… If the RGB is getting converted to the CMYK color space, then why not prefer files be made in CMYK to begin with? Also, I thought the Brother GT-3 printed in sRGB…has Printful changed its DTG printer type? Sorry, but I want to be sure I give the bright and pastel colors in my baby clothing designs the best chance they can get!

        1. Nora Inveiss

          Hi Jacki,

          No need to apologize! You’re correct, the Brother printers are programmed to use RGB color values. So to simplify the whole process, we ask for RGB files right off the bat, so we only convert to CMYK once (as opposed to CMYK-RGB-CMYK).

          1. John

            That wouldn’t be a problem. CMYK to RGB would do nothing because CMYK has less color options than so RGB, going from CMYK to RGB would not effect the image. going from RGB to CMYK loses colors so it conforms the image to the new palette.

  6. Raquel

    I’m new to this so I’m trying to upload files but they’re in AI and some of them look transparent on black tees. What am I doing wrong and do I need to just submit all in .png or .jpg. Should they have a transparent background or is white ok? I’m clueless as what program to use to get it how you guys want. Any help would be appreciated.

    1. Nora Inveiss

      Hi Raquel,

      You can find some helpful info in the “print file guidelines” tab within each product page in Printful’s product catalog. Couple of quick tips:

      1. You should submit your files in either .png or .jpeg formats
      2. Your files should have a transparent background
      3. The program you use is up to you! We find that the majority of our customers use Photoshop.

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