Why does my printer show a paper mismatch error?
A paper-size mismatch usually means the print job's requested size does not agree with the paper size configured for the selected tray. Depending on the printer, that configuration may come from tray guide positions, control-panel settings, driver settings, or automatic media detection. The tray configuration can disagree with the loaded paper. While some printers use sensors to detect sheet width, many rely on tray guide positions or manual control-panel registration, so loading paper does not always update the device automatically.
The three settings that must agree
- Document page size: the dimensions saved in the file or application.
- Printer driver paper size: the destination sheet requested by the print job.
- Sheet physically loaded: the actual paper in the selected tray, including its registered size on the printer.
For a paper-size or mismatch warning, one of these three usually disagrees; check them before assuming a fault. For cropped or incomplete output, check printable margins, the application's print area and scaling too. If you intentionally print onto a different size, select that destination and scale the source document to fit.
Fix it on Windows
Register the paper in the tray
Load a uniform stack and confirm its actual size and media type on the printer’s control panel when prompted. Do not confirm a saved A4 setting if you loaded Letter.
Match the Windows driver to the loaded sheet
In Windows 11, open Start > Settings > Bluetooth & devices > Printers & scanners > your printer > Printing preferences. In Windows 10, use Settings > Devices > Printers & scanners > your printer > Manage > Printing preferences. Select the loaded Paper Size and Paper Source. Drivers may place these under Paper/Quality, Layout or Advanced.
Stop automatic tray selection choosing the wrong stack
Open File > Print > Printer Properties and select the correct Paper Source for the job. In Acrobat Reader, review Choose paper source by PDF page size: turn it off when deliberately scaling all pages onto one loaded size.
Send one fresh test page
Cancel the old job in the print queue and send one page again after changing the settings. A queued job can retain the earlier size. Check the preview and printed margins before printing the remaining copies.
Fix it on macOS
Confirm the printer’s tray registration
On the printer control panel, open its Paper or Tray Settings and confirm the actual stack size and type. The wording is model-specific; macOS cannot correct a wrong tray registration on every printer.
Match the macOS print job to the loaded sheet
Open File > Print, select the intended printer and choose Paper Size. Expand Show Details if your version displays that button. Under Paper Feed or the manufacturer’s printer options, select the tray holding that sheet. These controls vary by application, driver and AirPrint support.
Check saved presets
In File > Print, check Presets and choose Default Settings before reselecting the loaded paper size and tray. A saved preset may restore a different source or format.
Send one fresh test page
Cancel the old job in the print queue and send one page again after changing the settings. A queued job can retain the earlier size. Check the preview and printed margins before printing the remaining copies.
If it still will not print
- Rest the tray guides against the stack without bowing the sheets. Use one size and type per stack.
- Check the selected tray. An automatic source can choose a different stack from the one you checked.
- For custom paper, confirm that the size is defined in the driver and supported by the chosen tray. A custom preset cannot make a narrow paper path wider.
- If the settings agree and a simple test still fails, check the manufacturer's support page for your exact model's driver and firmware updates. Follow its update instructions and keep power connected throughout.
Some models allow a mismatch override or Continue option. That may let the job print, but the margins can sit unevenly on the sheet or content can be cut off. Use it only after checking what will be printed; it is not a replacement for matching the settings.
Check the actual paper dimensions
A4 vs Letter: dimensions and print scaling
A4 → Letter: use 94% to fit the full sheet in portrait orientation, rounded down. Printer margins may require a smaller scale. The A4 vs Letter comparison explains both directions.