Apparel printing has one unusual property: the design is printed at a fixed physical size, typically 25–30 cm wide across a chest. That fixes your pixel requirement precisely.

Resolution

  • 300 DPI at the actual print size is the standard. A 30 cm wide print needs 30 ÷ 2.54 × 300 ≈ 3543 px wide.
  • Common safe sizes: 4500 × 5400 px for a full front print, 1800 × 1800 px for a pocket or small chest print.
  • 150 DPI can pass for large, soft-edged artwork, but text and line art at 150 DPI look visibly rough on fabric.

Never upscale to reach these numbers. Fabric is textured and unforgiving; interpolation artifacts that hide on screen become fuzzy edges on cloth.

Transparency Is Mandatory

Your file must be a PNG with a transparent background. If you upload a JPEG or a PNG with a white background, the printer prints that background — a white rectangle around your design on a black shirt. This is the single most common print-on-demand mistake.

Also check for near-white pixels: an off-white halo left from a poor cutout prints as a visible grey outline. Inspect your file on a dark background before uploading.

The Print Methods Differ

  • DTG (direct-to-garment) — inkjet onto fabric. Handles photographs and gradients, unlimited colours. Needs high-resolution transparent PNG. Colours on dark garments require a white underbase, which slightly mutes them.
  • Screen printing — one screen per colour. Best for bold, limited-colour designs and large runs. Wants vector artwork with separated flat colours; gradients need halftones and cost extra.
  • Vinyl / HTV — cut shapes of coloured film. Needs vector outlines only, no gradients, no photographs. Great for text and simple logos.
  • Sublimation — dyes the fabric itself; works only on polyester and only on light garments, but has no hand-feel and no edges.

Match your artwork to the method before designing, not after.

The Dark Garment Problem

On dark fabric, DTG lays down a white underbase then prints on top. Consequences:

  • Very light or semi-transparent areas may show the underbase as a grey haze.
  • Soft shadows and feathered edges can print with a visible white fringe.
  • Pure black areas on a dark shirt are often better left unprinted, letting the fabric show through — but that requires designing them as transparent, not black.

Design for dark garments deliberately: use bold shapes, avoid subtle transparency at the edges, and preview your PNG against the actual garment colour.

Before Uploading

Transparent PNG, sRGB colour, 300 DPI at final print size, no white halo, no gradients if screen printing, text converted to outlines for vinyl, and the design centred within the platform's stated print area. Order a sample of anything you intend to sell — fabric colour, ink absorption and scale all look different in person.