What “exact size” means
An exact-size print has a physical dimension that can be checked with a ruler after printing. A file can contain thousands of pixels without specifying a reliable centimetre size. The print workflow must map image pixels onto a page with physical dimensions, then avoid changing that page scale.
Actual Size Lab creates an A4 PDF because PDF pages are described in points, where 72 points equal one inch. A4 is 210 × 297 mm. The tool converts the requested image size to points and centres the image on that page.
Prepare the source image
Start with the original image where possible. Cropping does not automatically reduce quality, but exporting or sending the image through a messaging platform may. Check the source pixel dimensions shown by the tool.
Do not artificially enlarge a tiny image and assume it gained detail. Resampling can create more pixels, but it cannot restore detail that was never captured.
Create the physical-size PDF
- Open the printer on the home page.
- Choose the image.
- Enter the required width and unit.
- Check the automatically calculated height.
- Review effective PPI and the A4 fit warning.
- Leave the 100 mm verification line enabled for the first print.
- Create and download the A4 PDF.
The file is generated in your browser. A transparent source is placed onto a white background because the PDF uses a JPEG image stream for broad compatibility.
Print on Windows or Microsoft Edge
Open the PDF in a viewer that exposes scaling controls. In Microsoft Edge, the print interface includes an Actual size option that prints without scaling. Confirm A4 paper and avoid Fit to printable area when exact dimensions matter.
Printer-driver wording varies. Look for 100%, Actual size or No scaling. If the only option is Fit, verify the 100 mm line and adjust the workflow.
Official reference: Microsoft Support: Print in Microsoft Edge.
Print on macOS
Open the PDF in Preview or another PDF viewer. Select A4 and keep scale at 100%. Turn off “Scale to fit paper size” when it would alter the page. Apple notes that percentages below 100 reduce the output and percentages above 100 enlarge it.
Official references: Apple: Print settings on Mac and Apple: Reduce or enlarge pages.
Verify the first print
Measure the optional line from end mark to end mark. It should be 100 mm. A 99 mm line indicates a one-percent reduction; a 102 mm line indicates a two-percent enlargement. If the reference is wrong, the image is wrong by the same scale factor.
The PDF contains a 50 mm image and the reference prints at 98 mm instead of 100 mm. The workflow scaled the page to 98%. The image will be about 49 mm wide.
Limits and appropriate use
Even a correctly constructed PDF cannot control mechanical tolerances, paper expansion, feed skew, borderless overspray or a driver that overrides the chosen setting. For crafts, mock-ups and ordinary photo sizing, a measured test print is usually sufficient. For regulated, engineering or manufacturing tolerances, use calibrated equipment and a documented process.