Customer art is usually good enough to screen print if it is vector, such as an .ai, SVG or PDF with real vector shapes, or if it is a raster image with about 300 pixels per inch at the size it will print. A 12 inch wide chest print therefore needs roughly 3,600 pixels across. Underbase, a Windows separation app, opens all of these, sizes the print from the file’s resolution tag or the print width you type, and shows the plates at true size, so you can see whether the art holds up before any film is made.
Many reprints start with art that was never big enough. Checking takes a minute; finding out at the light table costs a screen.
Open the customer’s file, set the print width, and see the plates at true size.
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What resolution does screen printing art need?
Print shops publish this in their art guidelines. Danger Press, a screen printing shop, says in its artwork requirements that raster artwork should be at least 300 DPI at the actual size it will print on the garment, not 300 DPI at thumbnail size, and that vector artwork sidesteps the issue because it scales to any size. It lists Illustrator, EPS or PDF with fonts converted to outlines as best, and layered PSD, TIFF or PNG at 300 DPI at full print size as acceptable. Low-resolution JPEGs, screenshots and images pulled from a website usually need to be recreated.
That is a typical standard, checked on 17 October 2026. Your own shop may accept less for simple shapes, and many shops do, but 300 at print size is the safe starting point.
How many pixels do I need for common print sizes?
| Print location | Print width | Pixels across at 300 ppi | Pixels across at 150 ppi |
|---|---|---|---|
| Left chest | 3.5 in | 1,050 | 525 |
| Left chest, large | 4 in | 1,200 | 600 |
| Youth front | 10 in | 3,000 | 1,500 |
| Adult front | 12 in | 3,600 | 1,800 |
| Oversize back | 14 in | 4,200 | 2,100 |
Print widths are common examples, not standards. The pixel numbers are width multiplied by resolution.
A quick check: divide the image’s pixel width by the print width in inches. If a 1,200 pixel logo is going 12 inches wide, it has 100 pixels per inch, a third of the usual target.
How do I tell if a file is really vector?
- SVG, .ai, EPS and PDF can be vector, but are not always. A PDF can contain a single pasted JPEG. Zoom in a long way: vector edges stay sharp, raster edges turn into squares.
- Fonts. Ask for text converted to outlines, or the font file, so lettering prints as drawn.
- Hidden low-res inside. A vector file with an embedded photo is only as sharp as that photo.
What can I do with a small JPEG?
Be honest with the customer and pick one:
- Ask for the original. The designer or the company’s marketing team often has the vector logo. This is the best result by far.
- Print it smaller. A 1,200 pixel logo is fine at 4 inches on a chest.
- Redraw it. Simple logos can be traced or redrawn in a vector editor. Charge for the time.
- Use index separation for photos. For shaded art at a modest size, index separation dithers the pixels into a few inks, and the dither hides some softness. It will not add detail that is not there.
Upscaling software can make a file bigger, but it guesses at detail. If you use it, proof the result at true size before you separate.
Check how the customer’s art looks at true size before it reaches film, in the 15-day free trial.
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How does Underbase size and show customer art?
Underbase is built around the files customers send:
- Open almost anything. PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF and Illustrator (.ai) files open from Open artwork, by dropping on the window, or from a bundled sample.
- Vectors at true size. Vector files are rasterized at 300 dpi at their true size, so a vector logo always has enough resolution.
- Rasters from their tag. Raster files are sized from their resolution tag. When a file has none, Underbase uses 300 dpi and lets you edit it or type the print width, in inches or millimeters.
- The right mode. Spot mode suits clean logos: each exact color belongs to one ink, close shades are grouped, and anti-aliased edges are shared between neighbors. Shaded JPEGs open in index mode, where pixels dither between a fitted set of inks under a dither strength control.
- Look at the plates. Preview each plate, check Output dots at the output resolution, and see the underbase as it will print on film.
- Generate at true size. The film PDF puts every plate on the sheet at true size with registration marks, and each sheet’s footer records the print size.
Typing the real print width is the important step. A logo that looks crisp on screen at its tagged size may be soft once you set it to 12 inches, and the plate preview shows that before you print film.
What will Underbase not do to the art?
Underbase separates the pixels and shapes in the file you open. Its product page lists no vectorizing, tracing or upscaling feature, so redrawing a logo or rebuilding a low-resolution image belongs in a design program first. It reads the artwork and never writes to it.
When is another tool better?
- Redrawing. Vector editors are the right tool for rebuilding a logo.
- Heavy retouching. Photo editors suit cleanup of a damaged image before separation.
- Shops that outsource art. If an art service prepares files for you, ask them to deliver at true size and the shop’s resolution, then use Underbase for separations and film.
Frequently asked questions
Is 150 dpi good enough for screen printing?
For bold, simple shapes it may print acceptably, but edges can look soft, and many shops ask for 300 at print size. Check the plate preview at true size before deciding.
What does Underbase do if the JPEG has no resolution tag?
It uses 300 dpi and lets you edit that value or type the print width directly.
Does Underbase convert a JPEG to vector?
No. It separates the pixels into plates. If the art needs to be vector, redraw it in a vector editor first.
Can I open the customer’s PDF directly?
Yes. Underbase opens PDF and Illustrator (.ai) files, rasterizing vector content at 300 dpi at true size.
Which Windows version does Underbase need?
Windows 11 version 24H2 or later on an x64 PC. 8 GB of RAM is recommended for very large artwork.
Try Underbase
Underbase is a one-time purchase in the Microsoft Store, with a 15-day free trial. Open a customer file you were unsure about, set the real print width, and look at the plates. For more, see screen printing color separation software, the film positive checklist, or the Underbase product page.
Catch weak art before it costs you a screen.
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Last updated 17 October 2026. Published by Automata Labs, a software company in Canada.