The calculation behind the presets
To calculate pixels, multiply the length in inches by the desired pixels per inch (PPI). For millimetres, divide by 25.4 first. Round each result to a whole pixel. For example, 50 mm ÷ 25.4 × 300 is about 591 pixels. At the same resolution, 70 mm becomes about 827 pixels.
The print presets use 300 PPI as a working reference, not a guarantee required by every printer. Printer dots per inch (DPI) and image pixels per inch are different measurements. Creating more pixels from a small original does not recover missing detail.
| Physical canvas | Pixels at 300 PPI, rounded | Typical use |
|---|---|---|
| A4 · 210 × 297 mm | 2480 × 3508 | Image-based page copy |
| US Letter · 8.5 × 11 in | 2550 × 3300 | Image-based page copy |
| 4 × 6 in | 1200 × 1800 | Photographic print |
| 35 × 45 mm | 413 × 531 | Dimension reference only |
Prepare the canvas, then set the print size
- Search the destination list for A4, US Letter, or the physical size you need. Read the selected dimensions and any notice.
- Use Fit the whole photo inside when all document edges matter. Review the padding and orientation. The tool does not straighten a photographed page’s perspective or remove shadows.
- Leave Output dimensions at 100% for the listed pixel reference. Prepare and download the image.
- Open the file in your print software. Explicitly set the intended physical size and review its scaling settings. Automatic fill or fit-to-page can change the size.
- For a size-sensitive job, make a test print and measure it with a ruler. Ask the print provider about margins, paper and bleed before ordering.
Why a correct file can print at the wrong size
PixelPrep Tools creates the specified pixel dimensions but does not promise a particular embedded DPI/PPI metadata value. A print application may use its own resolution assumption or scale to the printable area. A 600 × 600 image is 2 × 2 inches at 300 PPI, but 4 × 4 inches at 150 PPI.
Output scale also matters. Reducing a print preset to 50% halves each pixel dimension. You can still place that file at the same physical print size, but it then supplies half as many pixels per inch. That may reduce sharpness.
An image of a document is not a PDF
A4 and Letter destinations output an image, not a multipage PDF or an editable document. They do not recognize text, validate signatures, or make an inaccessible scan searchable. If a receiver requires PDF, use an appropriate document export tool rather than changing the image’s extension.
For a form or receipt, inspect the smallest text at full size. Keep the source copy. A tidy canvas does not compensate for a blurred capture, missing page corners, glare, or information that was never present in the original.