A logo lands high on the shoulder. An edge goes soft. A white rectangle appears around a mark on a black tee. Most of the faults that look like printer problems start in the file, and the print on demand artwork requirements that fix them are short: resolution measured at the final printed size, sRGB color, clean transparency, and a format that holds all three. Sort those out and the fixable faults go away. What is left is the supplier question, which no file prep answers.

What DPI do I need for print on demand?

300 DPI at the final printed size. A 12 x 16 inch front print needs roughly 3600 x 4800 pixels. 150 DPI is the practical floor, and only for large artwork with no fine detail. DPI alone proves nothing: a 72 DPI web image retagged as 300 DPI carries exactly the same detail it always did.

Pull a 1200 x 1200 image off a website, set it to 300 DPI in your editor, stretch it across a 12 inch chest, and you have a 100 DPI print wearing a 300 DPI label. Upscalers, AI ones included, manufacture new pixels out of the ones already there. On screen that reads as smoothing; on fabric it reads as mushy letterforms and plastic-looking gradients. Redraw at size, or work in vector and export the raster at the size you actually need.

What image size do I need for print on demand?

Build the canvas at the real dimensions of the print area, then export at 300 DPI. Common placements land close to these numbers.

• Front or back, standard: 12 x 16 in — 3600 x 4800 px

• Full Airventory DTG area, 60 x 60 cm: 23.6 x 23.6 in — around 7090 x 7090 px

• Left chest: 3.5 to 4 in wide — 1050 to 1200 px

• Sleeve: 3 x 12 in — 900 x 3600 px

• Tagless neck label: around 2 x 3 in — 600 x 900 px

Leave a margin inside the print area. Artwork built hard to the boundary has nowhere to go if the garment sits slightly differently on the platen, and whatever sits closest to the edge is the first thing to go. Keep type, borders and lockups inboard; let backgrounds take the outside.

RGB or CMYK for print on demand?

Export sRGB, profile IEC61966-2.1. That is what our line takes. Send CMYK and the RIP converts it anyway, usually to a duller result you never approved. Neon and fluorescent values will still print flatter than a backlit screen suggests, because no ink reaches them. If a color is load-bearing for the brand, judge it on a sample under daylight.

Do I need a transparent PNG for print on demand?

Yes. PNG-24 with a real alpha channel is the safe default for anything printed on a garment. JPEG cannot store transparency, so a JPEG logo arrives sitting on the white rectangle it was saved on, and on a black tee that rectangle prints. SVG is accepted by some platforms and refused by others; Amazon Merch takes PNG only.

Halos come from background removal done with a wand tool on an anti-aliased edge. The soft pixels at the boundary still carry the old white background, and a DTG underbase turns them into a visible outline. Zoom to 400% over a black layer before exporting. Gray fringing you can see there will be on the shirt.

Semi-transparency is the other trap. DTG builds its white underbase from the alpha mask, so a layer at 40% opacity, a soft drop shadow or a feathered glow gets read as coverage. You get solid or grainy patches where you designed a fade. If the soft edge matters, build it yourself as a halftone dot pattern at full opacity, so you decide what the RIP sees.

Print on demand artwork requirements by print method

DTG wants sRGB PNG with a hard alpha edge, and it rewards fine detail because the ink sits down in the fiber. What holds that detail is the knit underneath. Commodity wholesale blanks — Bella+Canvas, Gildan, Next Level — are built for print volume: thin, open, loosely knitted surfaces that scatter fine line work, take pretreatment unevenly and shift from lot to lot, so one 300 DPI file lands two different ways on two shirts sharing a style number. Airventory prints DTG in our own facilities, up to 60 x 60 cm at a fixed 1200 DPI, onto our own 250-450gsm combed cotton made to one spec, so the detail your file carries is the detail the fabric can hold. A 1200 DPI machine resolves everything a 300 DPI file gives it, and nothing beyond.

DTF is a different object: pigment on a film, bonded to the fabric with hot-melt adhesive. Across a big full front it does not breathe, it stiffens the drape, it creases along fold lines and it lifts at the edges, because the film cannot flex the way a knit does. Small is where it belongs — tagless neck labels, care labels, a left chest hit, a sleeve, and polyester, fleece, nylon, caps and totes, where DTG ink has little to bond with. Prepare the art as you would for DTG; the film is cut to your transparency.

Branding artwork deserves the same discipline. Woven neck labels, printed tagless labels, hangtags, inserts and branded polymailers are applied on demand with zero minimums, and each wants its own drawing of your mark. A woven label reproduces a simplified, single-weight version well; the thin strokes in a full-color logo scaled down to label size will not survive the weave. Embroidery is a stitched process with its own rules, so treat an embroidered mark as a separate artwork job.

Why does the same file print differently every time?

Because on marketplace POD it is frequently a different printer. Printful, Printify and Gelato route each order to whichever third-party partner accepts it, and those partners run different machines, inks, pretreatment and blanks. The file did not change; the hands did. Your tenth drop stops matching your first, and file prep cannot correct a supply chain that reassigns itself between orders. Our own facilities work to one spec, which is what turns artwork prep into something you solve once.

The file is the part of this job you control end to end: build at print size, export sRGB PNG with a true alpha channel, and study the edges at 400% over black before you upload. Everything after that belongs to whoever prints it.