| Chosen PNG width | Chosen DPI | Calculated print width |
|---|---|---|
| 1024 pixels | 150 DPI | 173.40 mm |
| 1024 pixels | 300 DPI | 86.70 mm |
| 1024 pixels | 600 DPI | 43.35 mm |
Separate file detail from print dimensions
A PNG contains a fixed pixel grid. Its physical-resolution metadata gives a print application a suggested mapping from pixels to inches, but the application can override that mapping. Increasing the DPI label without increasing pixel dimensions does not create new image detail.
Tidy QR writes a physical-resolution chunk into exported PNG files. The selected width controls the number of pixels, and the selected DPI controls the intended physical width. Check the placement dimensions in your layout application instead of assuming it will honor the metadata automatically.
Use vectors for flexible placement
SVG describes the shapes of the QR modules. A vector PDF does the same within a page with a defined physical size. Those formats allow the print workflow to rasterize the modules at the output device's resolution. A logo inserted into the code remains a raster image even when the surrounding modules are vectors.
Keep the code square when placing it. Do not apply perspective, stretching or a nonuniform resize. If you need to crop a PDF page for a layout, preserve the full quiet zone and any frame beyond it. Export a final proof and check what the print supplier actually receives.
Avoid fractional module edges when possible
DENSO WAVE discusses module size in printer dots and recommends enough dots per module for stable output. A raster resize can place an edge between pixels and introduce gray interpolation. Vector output lets the printer handle that process later, while a carefully sized PNG can also work well.
Ask the print supplier about the actual process and material. Ink spread, thermal head resolution and reflective surfaces can affect small details. Use the print calculator as a planning tool, then approve a real sample. The final test should include the design file, printer settings and material together.
Put this into practice in the QR generator, then inspect the decoded payload before printing.
Sources
Last checked: . Examples are illustrative inputs, not measured results.
- Determining the QR code area, DENSO WAVE. Checked 2026-10-29.
- Setting the module size, DENSO WAVE. Checked 2026-10-29.
- Implementation specifications, checked against source code, Tidy QR. Checked 2026-10-29.