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DTG printing: RGB or CMYK and black shirts.

DTG in RGB or CMYK? 150, 300 or 360 DPI, sRGB, not CMYK, black knocked out or underbased on a black shirt: what Printful, Printify, Gelato and Epson ask.

Sources read 2026-10-19 · updated 2026-10-31 · next re-read due 2027-01-17

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How the process treats your file

DTG is an inkjet pass of water-based CMYK pigment onto pretreated cotton. On a light garment the RIP prints colour only. On a dark one it lays down a white underbase first and prints colour on top, and Printful says the underbase is decided automatically from the design and the product. The RIP, not the seller, normally draws that white from the file’s alpha channel (CADlink, Epson). That is why every platform that names a DTG format points to PNG with a transparent background.

The same pixel can print two ways. Epson’s guide says pure white (255, 255, 255) is left unprinted in light-garment mode, while Brother’s software treats RGB=255 as white ink by default.

Resolution advice does not line up either. Printful asks for at least 150 DPI; Printify’s help centre recommends 300 DPI and says less may do, while a Printify blog calls 300 a minimum; Epson’s Garment Creator recommends 360 dpi for its own printers. Where the sources agree is the edge of the design: semi-transparent pixels on a dark shirt.

What the printers specify

Size the file to the platform’s placement, not the machine’s platen.

Resolution at print size

Floors sit at 150 DPI (Printful, Gelato, Fourthwall for apparel), and 300 is the common recommendation (Printify). Redbubble also sets pixel minimums, which decide which products a file can be listed on.

  • Printful (platform): “At least 150 DPI” (Printful: DPI and print file size); recommends “at least 150 DPI for DTG products” (Printful: 150 vs 300 DPI); also “150–300 DPI, depending on the product requirements” (Printful: Preparing your print file). Not over 600 or under 150 (Printful: Graphics guide). Its DTG page sets the ceiling lower: “It’s also best not to exceed 300 DPI” (Printful: DTG file guide).
  • Printify (platform): 300 recommended, “a lower resolution file might also be sufficient”. — Printify: Print file requirements. Its blog calls 300 a minimum, then says “You don’t strictly need it for a small print”. — Printify: PNG setup for t-shirts
  • Gelato (platform): minimum 150 DPI; 300 “for the best possible print quality”. — Gelato: DTG design files
  • Redbubble (platform): minimum pixels per product: Premium T-Shirts 2875 × 3900, Men’s Graphic T-Shirts 3873 × 4814, Other Apparel 2400 × 3200; print method not stated. “DPI and PPI don’t affect your final uploaded image.” — Redbubble: Dimensions & Format
  • Fourthwall (platform): “At least 150 DPI at print size for apparel”, 300 for other printed products; “pixels = print size in inches × DPI”, so a 10 × 12 inch apparel print needs 1500 × 1800 px. Each product has its own requirement. — Fourthwall: Artwork best practices
  • Epson (maker/RIP): Garment Creator recommends 360 dpi; 180 dpi appears only as a fix for slow imports. — Epson: Garment Creator guide
  • Kornit (maker, print modes not file, 2019): 363 to 636 DPI on Storm, Thunder and Paradigm, 600 × 1200 on Breeze; “Usually there is no need for more than 454DPI for printing on cotton.” — Kornit: FAQ, 2019
  • T-Biz / T-RIP (RIP vendor article, 2022): “the correct physical size and 200 to 300 dpi”, given as a target to upsample low-resolution web images to, which the platforms above warn against. — T-Biz: Artwork for DTG
  • Brother (maker/RIP): not stated. — Brother: Graphics Lab manual

File format

PNG with transparency is the one format every source accepts for a dark shirt.

Colour mode and profile

Every platform here wants an sRGB or RGB upload, so one export serves them all; they differ on whether to design inside the CMYK gamut.

  • Printful (platform): sRGB IEC61966-2.1, no Adobe RGB or ProPhoto; early CMYK “can unnecessarily reduce the available color information”. Proof space PSO Coated v3. Rendering intent: not stated. — Printful: RGB or CMYK
  • Printify (platform): works in RGB; a CMYK upload is converted “and the colors might shift significantly.” — Printify: Colour profile
  • Gelato (platform): sRGB, and design “within the CMYK color gamut”. — Gelato: DTG design files
  • Fourthwall (platform): “Use sRGB for every product.” “Don’t convert your artwork to CMYK yourself: printers convert to CMYK during production, and PNG files can’t store CMYK.” — Fourthwall: Artwork best practices
  • Redbubble (platform, process not stated): design in CMYK, upload RGB. — Redbubble: Dimensions & Format
  • Epson (maker/RIP): RGB and sRGB recommended; no CMYK in PNG or BMP. — Epson: Garment Creator guide
  • Kornit (maker, 2019 capture): the software “can redefine the file color”; no file colour requirement found. — Kornit: FAQ, 2019
  • Brother (maker/RIP): not stated. — Brother: Graphics Lab manual

Transparency and alpha

Make every pixel fully opaque or fully transparent. Some RIPs scale white by opacity, but the seller cannot see which RIP runs the job.

  • Printful (platform): ink spreads over missing information, leaving “a lot of gaps with a visible white base”, worst on dark fabric. — Printful: Transparency in DTG files. “Avoid semi-transparent edges or fades for DTG/DTF printing.” — Printful: Preparing your print file
  • Printify (platform, blog): any pixel above 0% opacity gets solid underbase; “exactly two kinds of pixels: 100% solid, or 100% transparent.” — Printify: PNG setup for t-shirts. The help centre is softer: semi-transparent elements “can look whitish, grainy, faded, or discolored”. — Printify: Print looks different
  • Gelato (platform): lowered opacity “may not print well with DTG technology.” — Gelato: DTG design files
  • Inkthreadable (platform): 0% or 100% is “perfect”; in between, results “are usually unpredictable”. — Inkthreadable: Gradients & transparency
  • Epson (maker/RIP): “the amount of ink fired decreases depending on the transparency”, and it recommends RGB data that includes transparency. — Epson: Garment Creator guide
  • CADlink Digital Factory (RIP): “Adaptive” sets underbase density from opacity; “Treat all semi-transparent as opaque” does not; no defaults stated. — CADlink: Layer tab
  • Brother (maker/RIP): RGB=255 prints white by default; a drop shadow over RGB=255 “may become white.” — Brother: Graphics Lab manual
  • T-Biz / T-RIP (RIP): “no color (not even white) around the image.” — T-Biz: Artwork for DTG

White handling

The RIP builds the white layer; no platform read says it accepts a seller-supplied white channel.

  • Printful (platform): underbase need “is determined automatically based on the design and the product”; no white ink on white garments. — Printful: White underbase, Printful: Printing disclaimers
  • Printify (platform): underbase on dark garments, colour only on light ones; seller white not stated. — Printify: DTG gradients
  • Gelato (platform): underbase applied; seller white not stated. — Gelato: DTG design files
  • Epson (maker/RIP): white amount set automatically; Reduce White Area 0 to 20 px, default 2; Under White OFF leaves non-white areas “less resistant to washing and friction.” — Epson: Garment Creator guide
  • CADlink Digital Factory (RIP): separate chokes for white made in the design application and white generated in the queue; a choke of 2 pulls white 2 px in. — CADlink: Layer tab
  • Brother (maker/RIP): RGB=255 prints as white ink by default; underbase generation not stated. — Brother: Graphics Lab manual

Screen printing burns the underbase as its own screen and flash cures it before the colours: see Screen printing: White handling.

DTG on a black shirt: black on black

Sources split on black ink over a black shirt; if the black should be the shirt, leave it transparent.

Minimum line and text size

Nobody publishes a DTG number, light or dark.

Bleed and safe zone

Bleed is not applicable to DTG: there is no trim. The safe line and placement drift are what count.

Ink, gradient and colour limits

No source gives the seller an ink limit or colour count; what matters is how a gradient is built.

Large solid areas and blends

No maker publishes a limit on solid area or fabric; the warnings come from platforms.

  • Printify (platform, blog): a giant underbase patch “doesn’t breathe, making hoodies feel stiff”. — Printify: DTG underbase
  • Epson (maker): no area limit; printing without the underbase (Under White OFF) leaves non-white areas “less resistant to washing and friction.” — Epson: Garment Creator guide
  • Printful (platform): blends give “a faded/vintage outcome” with DTG. — Printful: DTG file guide

Where the sources disagree

Resolution: a floor against a recommendation

Printful requires at least 150 DPI at print size and prints DTG on Kornit. Printify’s help centre recommends 300 and allows less. Epson recommends 360 dpi for Garment Creator. Redbubble specifies pixel minimums and ignores the DPI tag.

Only Printful against Printify is like for like, and it is a floor against a recommendation. A file at 300 DPI at the real print size passes both; one at exactly 150 passes Printful and sits below Printify’s advice.

DTG in RGB or CMYK: sRGB upload, CMYK gamut

Printful: converting to CMYK before upload “can unnecessarily reduce the available color information”. Fourthwall: “Don’t convert your artwork to CMYK yourself”. Gelato asks for sRGB and the CMYK gamut in one article; Redbubble says design in CMYK, upload RGB; Fourthwall says keep the artwork in sRGB because “printers convert to CMYK during production”.

The upload profile is settled; the split is over who handles colours the inks cannot reach. Whoever converts first decides the gamut, and the file carries no record of that decision; keep an sRGB master.

Semi-transparent pixels: forbidden, or handled by the RIP

Printify’s blog: any pixel above 0% opacity gets solid white. Epson: ink fired “decreases depending on the transparency”. CADlink: Adaptive scales white by opacity, or a switch treats all of it as opaque.

A partly transparent edge (Printify’s 30% pixel) prints according to the RIP and its settings, and no platform says which it runs. No semi-transparency is a safe seller rule, not a description of every machine. Printify’s help centre is softer than its blog.

DTF films split on the same question: see DTF: Semi-transparent pixels.

Black on a black shirt: knocked out or underbased

Printful underbases a completely black design on a black garment. Gelato says leave black areas fully transparent. Printify states both behaviours in one article.

Knockout is a RIP setting (CADlink KnockMeBlackOut) chosen by the print shop; Epson’s nearest control, Under White OFF, drops the whole underbase, not black alone. The seller controls only the file: transparent where the shirt should show.

What fails on the floor

All eight cases are platform or vendor descriptions, not photos of a print beside its file.

Chalky or rubbery ring around the design on a dark shirt

Cause in the file: soft edges, glows or low-opacity shadows leave partly transparent pixels that get full white. Printify: a 30% transparent pixel can become “a 100% solid white dot underneath it”, and “the order comes back with a rubbery halo around your graphic”.

White box printed around the whole design

Cause in the file: no alpha channel (a JPEG, or a PNG on a white canvas). Printify: JPEG “forces a solid one, usually white”. T-Biz: the RIP “is not smart enough to know that this white should not print”.

The same failure on film: DTF: White box around the design.

Patchy gradient on a dark shirt

Cause in the file: a fade built from opacity instead of colour. Printify: “making the gradient appear uneven or patchy”.

Grey or dull black on a black shirt

Cause in the file: black artwork on a black garment with no knockout. Printify: black on black “can come out grayish or dull rather than glossy”.

Colour shift blamed on the file’s colour mode

Printful: wide-gamut RGB “can cause unexpected color shifts” and early CMYK conversion leads to “less accurate results”. Fourthwall: “Don’t convert your artwork to CMYK yourself”, because printers convert in production; its page no longer says what an early conversion does to colour. Printful blames a conversion done before upload; Fourthwall only rules it out.

Grainy, blurry print from Save for Web or an upscaled file

Cause in the file: a 72 DPI export, or pixels enlarged to hit a DPI number. Printful: Save for Web “often reduces your file to 72 DPI”. Printify: artificially increased resolution “can’t be detected by the enhancement tool”.

Order counted as blank

Cause in the file: white-only art on a white shirt, art outside the print area, or a design under 10 px. Printful counts all three as blank products.

Stiff hand on large solid areas

Cause in the file: a large solid graphic forces a full underbase patch. Printify says it makes hoodies “feel stiff”. Marketing prose, no measurement.

What shops ask on the forums

Three questions came up in at least two DTG or garment threads since 2024. The quotes are the askers’ opening posts.

“Is AI-generated art big enough to print on a garment?”

“Are the artworks for DTF or DTG will be print ready?” — T-Shirt Forums: Today, ChatGPT introduced Images 2.0, Print Ready? (April 2026). Also T-Shirt Forums: Poor Quality AI Art from Customers (March 2026), a print shop on customer files: “These tend to be very low-resolution PNG files with a million colors.” Both threads also carry the DTF guide’s first question; neither asker names DTG alone.

The guide’s sources give the floors (Printful 150 DPI, Fourthwall 150 DPI for apparel, Redbubble pixel minimums) and say not to upscale to reach them (Printify); none says what to do instead when a generator’s output is too small.

“Does going above 300 DPI help, and why does my DPI drop on export?”

“Does it matter if my design is above 300 DPI?” — Reddit r/printondemand: Question regarding POD and Canva (April 2026). Also Reddit r/printondemand: DPI issue (May 2026): “I have this issue, where the DPI falls below 200, easily.” And Reddit r/SCREENPRINTING: 300 Or 600 DPI? (March 2025), from a buyer of DTG tees.

Printful’s DTG page says “best not to exceed 300 DPI” while its graphics guide says not over 600, and Kornit (2019) sees no need above 454 on cotton; Redbubble ignores the DPI tag and sets pixel minimums, and Printful says Save for Web often drops a file to 72 DPI. No maker, RIP or platform page we read explains why a transparent-PNG export reports a lower DPI, or what a design tool’s export-size multiplier changes.

“Can my design fade to transparent, or glow, on a dark shirt?”

“Our logo uses a gradient that’s meant to fade to transparency.” — Reddit r/printondemand: Help with Gradients on DTG Shirts (July 2026). Also “Printful is telling me I can’t have semi-transparent elements.” — Reddit r/printondemand: Semi-transparent/glowy backgrounds with DTG? (July 2026). An older thread asks the same: T-Shirt Forums: How to print photos with faded edges on a black tee using DTG or DTF (May 2023).

The sources say to build the fade as halftone (Printify, Printful) or colour to colour (Inkthreadable); none warns that on a dark shirt a fade into the shirt colour still gets underbase, which is what the first asker reports, and none gives a halftone dot size.

Preflight before you upload

  • The file is a PNG with a real alpha channel, not a JPEG and not a PNG on a white canvas (Printful, Printify).
  • Every pixel is 0% or 100% opaque: check the alpha channel for soft edges, glows and shadows (Printify, Inkthreadable).
  • Gradients run colour to colour or as halftone dots, never into transparency (Printify).
  • Pixel size at the real print size gives at least 150 DPI, 300 if the file goes to more than one platform (Printful, Printify).
  • For Redbubble, the file meets the product’s pixel minimum, e.g. 3873 × 4814 for Men’s Graphic T-Shirts (Redbubble).
  • Not upscaled to reach that number, not exported with Save for Web (Printful, Printify).
  • Embedded profile is sRGB IEC61966-2.1, not Adobe RGB or ProPhoto (Printful); sRGB satisfies Gelato, Printify and Fourthwall too. No CMYK copy: a PNG cannot store CMYK (Fourthwall).
  • On a black shirt, areas meant to read as black are transparent, not filled black (Gelato); if that leaves nothing in the file, the shop has nothing to print and Printful treats it as blank (Printful).
  • No white-only artwork on a white shirt, nothing placed outside the print area, and the design itself not under 10 px (Printful).
  • Essential text and graphics sit inside the safe line, with 0.5″ of room for placement drift (Printful, Printify).
  • Fine lines and small text are checked at print size, since no DTG minimum is published (Printful).

Sources, checked on 2026-10-19

Forum threads

Could not check

  • Impressions Magazine, DTG artwork (2016), impressionsmagazine.com/?p=16003: HTTP 403 on 2026-10-25, also to a full Chrome user agent, and no Wayback copy exists. Its two rows (a trade-press lead on 300 dpi and a 14 x 16 in print, and advice to design in RGB) are removed; no count in this guide used them.
  • Kornit file requirements: kornit.com refused the fetcher (403, then 502); only the 2019 FAQ capture was readable.
  • Blocked or dead: helpdesk.caldera.com and caldera.com (403), equipmentzone.com, help.coldesi.com and support.prodigi.com (403), the Ricoh/Anajet choke page (404); CADlink blog posts, knowledge.polyprintdtg.com and a sites.tuni.fi Epson mirror were unreadable.
  • Not found or not read: Brother GTX driver settings, Epson F2270 and Garment Creator 2 docs, AcroRIP and NeoStampa, Spring/Teespring, per-placement pixel sizes in the Printful and Printify product tools.
  • Not stated anywhere read: rendering intent for sRGB to CMYK, a maker limit on ink coverage or solid area, and a photo of a failed print beside its file.

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