In this guide, we're going to be covering how to configure your Zebra GK420D printer for printing Royal Mail 2D Barcode labels.
Mac users
If you are using a Mac operating system (OSX) and you are experiencing issues with printing thermal labels then please get in touch with our support team at support@zenstores.com.
Please note: This will feed some blank labels through your printer.
Please note: Setting Dithering to None ensures that the newer 2D barcode is printed properly and will scan through the network.
Any other setting here reduces the accuracy of the 2D barcode to the point where the labels you produce may not scan through the Royal Mail network.
- Open Devices and Printers in Control Panel
On your Windows computer, open the Control Panel and select 'Devices and Printers'. Locate your Zebra GK420D in the list of installed printers (the printer name may vary). Right-click on it and select 'Printer Properties'.
- Navigate to Printing Defaults
In the Printer Properties pop-up window, click on the 'Advanced' tab. From there, select 'Printing Defaults' to open the settings where you can configure the paper size and format.
- Set the Paper Size to 4×6 Inches
In the Printing Defaults screen, set the Paper Format to 'inch'. Then set the Size Width to '4.00' and the Size Height to '6.00'. This matches the standard Royal Mail thermal label dimensions.
- Calibrate the Printer Media
Click on the 'Tools' tab, then click 'Action' and select 'Calibrate media'. Click 'Send' at the bottom of the page to run the calibration. Please note: this will feed some blank labels through your printer — this is expected behaviour.
- Set Dithering to None
Click on the 'Dithering' tab and select 'None'. This is a critical setting — any other dithering option reduces the accuracy of the Royal Mail 2D barcode to the point where labels may not scan through the Royal Mail network. Click 'Apply' and 'OK' to save.
- Start Printing Royal Mail 2D Barcode Labels
Your Zebra GK420D is now fully configured. You are ready to print Royal Mail 2D barcode labels directly from Zenstores. If you are on a Mac and experiencing issues with thermal label printing, contact the Zenstores support team at support@zenstores.com.
Frequently Asked Questions
Why do I need to set Dithering to None?
Setting Dithering to None ensures that the Royal Mail 2D barcode is printed with maximum accuracy. Any other dithering setting degrades the barcode quality to the point where it may fail to scan through the Royal Mail network, causing delivery issues.
Why does the printer feed blank labels during calibration?
Feeding blank labels is a normal part of the media calibration process. The printer uses this to detect the label gaps and align itself correctly for the 4×6 inch label size. You do not need to do anything — just allow the labels to feed through.
I'm on a Mac — can I still use the Zebra GK420D?
Mac users may experience issues when printing thermal labels with the Zebra GK420D. If you encounter problems, please contact the Zenstores support team at support@zenstores.com and they will be able to assist you directly.
What paper size should I use for Royal Mail labels?
Royal Mail thermal labels should be printed at 4.00 inches wide by 6.00 inches tall. Make sure the Paper Format is set to 'inch' in the Printing Defaults screen of your Zebra printer driver to match these dimensions correctly.
Do I need to reconfigure the printer every time I print?
No. Once you have saved the Printing Defaults settings and completed the calibration, the configuration is stored in the printer driver. You should only need to repeat these steps if you reinstall the printer driver or change computers.
