Print-on-Demand Image Requirements: A Guide for Gelato, Printful and Printify Sellers

With print-on-demand, you upload a design once and a print partner prints and ships each order. That means your file goes straight onto a customer’s shirt, mug or poster without anyone checking it. Getting the file right before you publish a product saves returns, refunds and bad reviews.

Resolution: 300 DPI at the print area size

Services usually recommend 300 DPI and accept 150 DPI as a minimum, measured at the size the design will actually print. If a shirt’s print area is 12 × 16 inches, a full-size design needs 3600 × 4800 pixels for 300 DPI, or 1800 × 2400 for 150 DPI.

Resolution problems are the main cause of “low resolution” warnings in product editors. If you see one, the design is being stretched beyond what its pixels support. How to fix a low resolution warning.

Start from the product template

Each product has a print area with exact pixel dimensions. Most services offer a downloadable template or list the sizes in the product details. Designing at that size from the start avoids stretching or cropping later, and the template shows the safe area where nothing important gets trimmed or wrapped around an edge.

Product by product

T-shirts, hoodies and tote bags

• Use a PNG with a transparent background. A white or coloured box around the design will print as a box on the fabric.
• Avoid soft, semi-transparent effects such as faint shadows, glows and feathered edges. Direct-to-garment printing handles partial transparency poorly, and these areas can look blotchy.
• Keep lines bold enough. Very thin lines and tiny text can disappear into the fabric.
• Think about garment colour. Dark ink disappears on dark shirts, and colours print slightly differently on coloured fabric.
• Size the design to the garment. A full print area is often around 12 × 16 inches on adult shirts, but many designs look better smaller.

Posters, canvases and framed prints

• These follow the normal print-size rules: 300 DPI for small prints, 150–200 DPI for large posters. See the pixel chart.
• Canvas wraps around the frame. On a gallery-wrapped canvas, a strip of the image folds around the edges. Keep faces and text away from the outer few centimetres.
• Match the shape. A design made for 2:3 will be cropped on a 4:5 frame. Make a version for each ratio you sell.

Mugs, bottles and phone cases

• Print areas are often long and thin (for wrap-around mugs) or include cut-outs (for camera holes on phone cases). Always use the template.
• Curved surfaces stretch designs slightly at the edges, so keep important details near the centre of each side.

All-over prints

All-over-print clothing and large textiles need very large files covering every panel. Services usually accept 150 DPI here because of the size; check the panel template for exact dimensions.

Colour

Print-on-demand services generally want RGB files in the sRGB colour profile and convert them for printing themselves. Don’t convert to CMYK unless the service asks you to. Very bright screen colours, especially neon greens, blues and pinks, will print less vivid. RGB vs CMYK explained.

File format and size

PNG is the standard for apparel because it supports transparency. JPEG is fine for posters and wall art without transparency. Services set maximum file sizes, so a very large PNG may need to be optimised before upload. Choosing the best file format.

Pre-publish checklist

1. Design at the product template’s pixel size.
2. Check the file reaches at least 150 DPI at print size, ideally 300 (the checker does this in seconds).
3. Use a transparent PNG for apparel and remove semi-transparent effects.
4. Keep important content inside the safe area.
5. Use sRGB colour.
6. Order a sample of each new product before selling it.