How to create your shirt design with AI

You can design your whole shirt on the website and get the print from an AI. Here's how to ask for it so it prints well on fabric, and the four things no prompt can fix that are worth knowing before you start.

Designing a kit with AI no longer means going anywhere else. In Design your shirt you tap “Design with AI” and choose: “I have a photo”, and upload up to four so we can copy what you like, or “Let the AI design it”, and describe it in words. You generate it right there, on the real pattern, and see it in 3D before you buy. Even so, printing on fabric by sublimation has its rules, and there are things no AI does well on its own. This is what we learnt by measuring one result after another.

We spent a whole morning testing prompts against the photo of a real shirt and measuring every result: how much colour it carries, how much it fades, how thick the finest detail is, whether it keeps the symmetry. This is what came out.

Which AI should you use? Whichever you like: everything here works for any AI that generates images. If you have no preference, choose one that doesn't stamp a watermark. And one that keeps the colours consistent between the front, the back and the sleeves: that's what has worked best for us, measuring piece by piece.

Two questions, and that's it

There are no prompts to copy and no in-between screens. Inside “Design with AI” you only have to decide two things:

Are you starting from something? If you have a photo —a render, another team's shirt that you like, a sketch—, “I have a photo”: drop it there, up to four, and you can remove and add them before generating. If you have nothing, “Let the AI design it” and describe it in words.

Do all the pieces have the same pattern? If it's a repeating print —stripes, camouflage, a gradient—, a single image works for everything. If there's a large motif in a specific place, no: the sleeve is landscape and narrow, and it would only take a strip from the middle of the front.

Generating uses up one generation. You get 5 free when you create your account, they go back up to 5 after every order and, if you want more, you top them up one at a time for €0.50. Nothing you do afterwards uses any up: changing any colour, making the sleeves the background colour, a plain back, the collar, moving and resizing names and numbers, viewing the 3D or zooming into the design, it's all free. And if a generation comes out faulty, it's repeated automatically once at no charge and you keep both saved to choose from.

Before using up another generation, try changing the colours. Often that's all it needs, and it costs nothing.

The real proportions

Each piece of the pattern has its own shape, and these are the measurements the fabric is cut to:

• Front: 53.8 × 72.9 cm — portrait 3:4
• Back: 55.9 × 76.7 cm — portrait 3:4
• Sleeve: 48.1 × 25.3 cm — landscape 2:1
• Shorts leg: 71.3 × 57.3 cm — landscape 5:4

The sleeve is the tricky one: its two top corners are lost completely when it's sewn to the shoulder, so nothing important can go there. Whatever you want to be seen, put it in the central band. The designer marks the recommended area of the sleeve with a dotted line. Outside it, it still gets printed, but the sleeve is sewn into a tube and it may end up under the arm. That's why it's worth looking at it in 3D: you see it while you design and, before the basket, full screen to confirm it.

Don't worry about size

It's the most widespread myth and the most frustrating one. Don't ask the AI for a number of pixels: it can't give it to you. None of the ones we've tried goes beyond about 1800 × 2400, and several stop at 1100 × 1450 — and they're all more than enough. With 1200 pixels on the long side it's perfect, and between 700 and 1200 it looks good.

Sublimation on fabric is much more forgiving than printing on paper. The reference 150 dots per inch are for paper; they don't apply here. Just ask for it “as large as you can” and move on.

What the AI gets wrong, and no prompt can fix

All of this happened to us while testing. It's not down to how you ask: it's how these tools are. You work around it, you don't fix it.

From one of our tests. Under the crest it was supposed to say PURA CALLE.

AIs misspell things. There you have it: we asked for a crest that said “PURA CALLE” and it returned “CURA CALE”; in another attempt, “RUA CALLE”. You can fix it in one message —“it says X, it should say Y, correct only that text”— but if you don't read it before uploading it, the shirt gets made with the spelling mistake on the chest. That's why the name and number go on top and afterwards, never inside the generated image. And you place them yourself: you move them, enlarge them, centre them and give each its own colour, separately: the name, the number, the chest number and the shorts number. And you choose the font: the EZ one, 14 more or your club's own. The AI paints the fabric and only the fabric: it comes out without crest, sponsors or numbers, and that's correct. All of that goes on top, you add it in two clicks, it comes out sharp and it's included.

Colours change between conversations. If you ask for the front in one chat and the sleeve in another, the red will come out similar but not the same. Separately you don't notice; when the body is sewn to the sleeve, you do. Make the pieces one after another, without closing the conversation. And if you've had to close it, redo them all, not just the one you're missing.

It answers with text and doesn't make the image. You paste in the brief and it replies describing what it would do, or asking you questions. It happens mostly with long texts. Don't argue: write “Generate the image now.” and it does it.

It draws the shirt being worn. Instead of the flat print it gives you a hanging shirt, a mannequin or a player. That image is no use: it has a collar, sleeves and shadows inside it. Reply “I don't want the shirt, I only want the fabric laid out flat”.

Touch-ups aren't asked of the AI: they're done by hand. Inside the designer you no longer ask the AI for anything in writing, and that's on purpose: asking it to “move the band up a bit” gave you something completely different and cost you a generation. Whatever can be changed is changed by hand and for free —any colour, the sleeves, the collar, the position of names and numbers—, and you see it instantly. You only generate again when you want a genuinely different design.

The size of the pattern changes from one piece to another. It once made us the sleeve with the motif six times bigger than on the front. When they're sewn together, it doesn't match at all. When you ask for the sleeve, tell it “same stripe thickness and same motif size as on the front”, and before uploading them put them side by side on the screen.

Some stamp their watermark. A grey sparkle about 3 cm wide in a corner. They add it when exporting, so asking them not to does nothing: you have to crop it out before uploading the image.

Fine grain is hit and miss. With the same text, one run gives you a clean design and the next one full of millimetre-sized grain, which blurs on fabric. It's not your prompt: it's the model's roll of the dice. If it comes out grainy, ask for it again.

Symmetry is never exact. None of them makes a perfect mirror: the left and right sides come out similar, not identical. On fabric, from 70 centimetres away, you can't tell. Don't waste ten generations fighting with it.

And what you can avoid yourself

These aren't AI faults: they're things we ask for without realising and that then get printed exactly as they are.

“Realistic” shadows, creases and seams. It's the most expensive mistake. If you ask it for a realistic photo, it paints the shadow of the fold and the shine of the spotlight… and that gets printed as grey ink: the shirt comes out dirty, with stains that won't go away. Always ask for it flat, with even lighting, without shadows or highlights. And if you're copying from a photo, tell it to ignore the lighting: a white photographed under coloured lights isn't white, and it'll copy it as grey.

A background or frame around the design. If you write “a shirt on a white background” it gives you exactly that: the design small in the middle of a white frame, and that frame gets printed. The print has to reach all four edges of the image.

The crest and sponsors inside the design. The AI doesn't copy them, it reinvents them, and they'd be stitched into the print forever. The base goes bare —just the fabric— and the crest, logos and sponsors are placed on top in the customiser, where you can move and change them.

Fluorescent and metallic colours. Sublimation prints with normal inks, and fluorescent and metallic colours don't exist as ink: fluorescent comes out as that same colour but dull, without the glowing effect, and gold and silver come out as an ochre and a grey. It can be done, but now you know what you'll receive.

Copying a branded shirt. “Make me the one from such-and-such club” or “put such-and-such brand's logo on it” will give you something similar, but we can't make it: they're registered trademarks. Inspiration, yes —“vertical red and blue stripes, V-neck”— and your own club's crest, as much as you like.

The crest goes separately

It isn't asked for together with the print. If your club has the original file, always use that. And if not, crop the crest from a photo —roughly, a square by eye with background around it— and ask the AI to improve the quality and remove the background. As it isn't rewriting the letters from scratch, they come out right. And if you don't have a crest, it can invent one for you too. In step 2 of “Design your shirt”, “Crest and logos”, you have the button “Making them with AI? We'll guide you step by step”. It gives you the exact text for both things, which works just the same for sponsors, with the fix for anything that might go wrong. And if the club doesn't have a crest, right there you'll find “No crest? Create one here”: you choose the shape, initials or name, year, colours and icon.

If there are several logos, give them all to it in the same conversation: that way they keep the same colours between them. And you don't need to cut them out neatly: we remove the background ourselves when you upload them.

Before uploading it

Read the letters if there are any, one by one. Open it full screen: if it looks mushy, on the garment it'll look the same but from 70 centimetres away. Check that it fills the rectangle, with no white strips. And that nothing important is right up against the edge, which is where the seams go. In PNG, JPG or SVG; no PDF or HEIC.

If you're still not convinced, upload it anyway. In the customiser you move it, enlarge it and choose whether it fills the piece or fits in whole. And before deciding anything, look at it in 3D with your image on it: you see it while you place it and, before the basket, full screen so you can confirm it. Nothing is made until you say yes.

Upload my design · The complete guide, with the reason behind everything