Free tool · Printing
Check a print file for DTF: size, DPI and gang sheet fit
Drop a PNG, JPEG or PDF and see what a print shop will see: its pixel size, the resolution at your print size, the colours in the design and how many copies fit on a gang sheet. The file is measured in your browser and never uploaded.
- Free, no sign-up
- No upload: runs in your browser
- PNG, JPEG and PDF
- Reads very large files
Drop your print file here
PNG, JPEG or PDF, any size. Large files are read in pieces, so even multi-hundred-megabyte gang sheets work.
Your file is read and measured in your browser. It is never uploaded to a server.
How it works
How to use this tool
Drop your file
Drag a PNG, JPEG or PDF onto the tool, or choose one. It is read on your device, in pieces, so large gang sheets open in a moment.
Set the print width
Enter the width you plan to print at. The checker works out the real resolution at that size, which is what decides how sharp the print is.
Read the checks
See whether the format, background, resolution and size suit DTF, with a plain explanation of anything that needs fixing.
Plan the gang sheet
Pick a sheet size to see how many copies fit and how they are laid out, or enter a quantity to get the film length you need.
What you get
What the tool tells you
Pixel size and DPI
The exact pixel dimensions and the resolution stored in the file, read from the PNG, JPEG or PDF data itself rather than guessed.
Resolution at print size
How many pixels land on each printed inch at the width you choose, and the largest size the file prints at 300, 200 and 150 DPI.
Design area without empty edges
The box that holds the visible design once transparent margins are left out: the size that actually gets printed and paid for.
Colour palette
The dominant colours as hex values with their share of the design, plus how much of it is transparent or semi-transparent.
DTF print checks
File format, transparent background, resolution, film width and soft edges, each marked as fine, worth a look or a problem.
Gang sheet fit
Copies per sheet for common DTF sheet sizes, drawn to scale, including layouts that turn some copies 90° to use leftover space.
Guide
The background, in short
| Size in inches | Size in centimetres |
|---|---|
| 22 × 12 in | 55.9 × 30.5 cm |
| 22 × 24 in | 55.9 × 61 cm |
| 22 × 36 in | 55.9 × 91.4 cm |
| 22 × 60 in | 55.9 × 152.4 cm |
| 22 × 120 in | 55.9 × 304.8 cm |
| 22 × 240 in | 55.9 × 609.6 cm |
| 13 × 19 in (A3+) | 33 × 48.3 cm |
| A3 (11.7 × 16.5 in) | 29.7 × 42 cm |
| A4 (8.3 × 11.7 in) | 21 × 29.7 cm |
What makes a file ready for DTF printing
A DTF (direct-to-film) printer lays your design on a film in colour, covers it with a layer of white ink, and the result is heat-pressed onto the garment. Only what is in the file gets printed, so the file has to be right before it reaches the printer.
Three things matter most. The background must be transparent, or it prints as a solid rectangle around the design. The resolution must be high enough at the printed size: 300 DPI is the usual target, and below about 150 DPI pixels start to show. And the edges should be solid, because the white layer under semi-transparent pixels tends to show through as a pale haze.
The checker measures each of these from the file itself and tells you which ones pass at the size you plan to print.
Why the DPI inside a file can mislead
The DPI stored in an image is a note, not a property of the pixels. A 1,200 pixel wide design marked as 300 DPI is meant to print 4 inches wide. Stretch it to 12 inches and it prints at 100 DPI, whatever the file says. Many files carry no DPI at all, and apps then assume 72.
That is why this tool asks for a print width and reports the resolution at that size. It also shows the largest size the file can be printed at 300 DPI, so you know how far a design can be scaled before it turns soft.
How it reads large files without uploading them
The checker runs on the file engine we built for Upload Center, our Shopify app for file uploads. The engine reads only the parts of a file it needs: the size and DPI of a 500 MB gang sheet come from a single small read at the start of the file.
To find the edges of the visible design it streams the image through a pixel scanner compiled to WebAssembly, in a background worker, a few rows at a time, so the file is never loaded into memory whole. And it never leaves your device.
Aim for 300 DPI at the size you will print. Bold designs with large shapes can look fine at 200 DPI, and about 150 DPI is the lowest worth printing. What counts is the resolution at the printed size, not the DPI value stored in the file.
No. The file is opened and measured by code running in your browser. It is not sent to us or to anyone else.
PNG, JPEG and PDF are measured in full, including the DPI stored in the file. Other image types your browser can open, such as WebP, are measured for their pixel size. PSD, AI and TIFF files are not read: export a PNG or PDF first.
Some files store no DPI value. That is common for images exported for the web. It doesn't make the file unusable: enter your print width and the checker calculates the real resolution from the pixel size.
Designs are often saved on a canvas that is larger than the artwork. With this option on, the tool measures only the box that contains visible pixels, so the print size and the gang sheet count reflect the design itself rather than the empty canvas around it.
It depends on the design size and the space left for cutting. With a quarter inch between copies, a 22 × 24 inch sheet holds 25 designs of 4 × 4 inches or 4 designs of 10 × 10 inches. The checker calculates it for your file and draws the layout.
Keep going
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Run these checks on every order, automatically.
Upload Center is our Shopify app for stores that print customers' files: uploads on the product page, automatic size and DPI checks, and prices calculated from the print size.