Good designs sell. Bad files don't print. This lesson is about both — making art people want, in files Printful won't reject.
The file specs (memorize these)
- Format: PNG with a transparent background. JPG is for photos, not apparel art.
- Resolution: 300 DPI minimum.
- Dimensions: For a t-shirt front, design at 4500 × 5400 pixels (15" × 18" at 300 DPI). That's the safe print area. Smaller artwork can be centered inside it.
- Color mode: RGB (not CMYK — Printful uses DTG and DTF printing which is RGB-based).
- File size: Under 200 MB. You'll rarely hit this.
Tools that work
You don't need expensive software. Any of these works:
- Free: Krita, GIMP, Photopea (browser-based Photoshop clone), Canva (Pro for transparent PNGs)
- Cheap: Affinity Designer / Photo ($70 one-time, no subscription)
- Pro: Adobe Photoshop / Illustrator / Procreate (iPad)
- AI-assist: You can use AI to brainstorm or generate textures, but be careful with style/IP — and clean up the output. Raw AI output usually looks like raw AI output.
Design rules that actually matter
1. Big, bold, readable from across the room
A shirt is seen at 10 feet, not 10 inches. Thin lines disappear. Tiny text looks like dirt. Use thick strokes, strong contrast, and test by viewing your design at 20% zoom — if it still reads, you're good.
2. Limit your colors
2-4 colors usually beats a rainbow. Limited palettes look intentional and print more consistently.
3. Mind the shirt color
Design for the garment. Light art on dark shirts, dark art on light shirts. If you want one design to work on both, use a high-contrast color palette and add a thin outline.
4. Beware white ink
On dark shirts, Printful prints a white underbase under your colors. This can sometimes leave faint white outlines around your art. Solution: avoid super faint edges and gradients to transparent. Use crisp shapes when in doubt.
5. Don't print to the edges
Keep a small safe margin inside the print area. Garments shift slightly during printing. Edge-to-edge designs risk getting clipped.
The "10 designs in a weekend" exercise
Open a blank canvas. Set a timer for 30 minutes per design. Make 10 designs based on your niche from Lesson 02. They won't all be good. That's the point. Volume teaches taste.
Copyright — don't get sued
Safe lanes: your original art, public domain (anything pre-1928 in the US), generic phrases, references that don't use protected names ("space cowboy" yes, "Mandalorian" no).
Action step
- Pick your design tool and learn its export-PNG-transparent workflow
- Make 3 designs this week, exported at 4500 × 5400, transparent PNG
- Open each on a phone — does it read at thumbnail size?
- Save them in a "Designs / Ready" folder, named clearly