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.
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 Design Maker 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?
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.
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!
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.
Some more good news: the Design Maker, 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.
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.
As a coffee fanatic, you wanted to create a custom t-shirt with a moka pot. You found a copyright-free design and uploaded it to the Design Maker.
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 Design Maker.
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?
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.
In the Design Maker, 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.
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.
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 Design Maker and continue designing.
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:
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.
Learn More: DTG vs. Screen Printing: Choosing the Right Apparel Printing Method for You
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.
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:
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!
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!
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.
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:
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
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.
Ready to start designing? Head to Printful’s Design Maker 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.
Marianna Zvaigzne is the Head of Brand Language at Printful. With the help of her team, she’s pinning down what it means to “sound like Printful” and keeps Printful copywriters on their toes with animated editing sessions and writing workshops.