> For the complete documentation index, see [llms.txt](https://docs.flowretail.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flowretail.com/docs/technical/configurations/calibrating-printers.md).

# Calibrating printers

Calibrating printers, and especially thermal label printers, is something that needs to be done every now and then in order to get the paper alignment correct and more.

## Calibrating a Zebra GK420d printer

### Step by step:

1. Turn on the printer.
2. Press and hold the Feed button for approx. 3-5 seconds, until the indicator LED flashes green once.
3. Release the Feed button.
4. The printer will feed out a few labels and complete the calibration automatically.

{% hint style="info" %}
Once completed, the printer stops feeding labels, and the status LED will show a solid green light.
{% endhint %}

### Verify Calibration (Print Configuration Label)

To ensure calibration was successful, print a configuration label:

* Press and hold the Feed button until the LED indicator flashes green twice, then release.
* A configuration label with printer settings will print out.

### Typical Problems Solved by Calibration:

* Labels feeding at incorrect lengths.
* Blank labels printed or labels feeding incorrectly.
* Labels stopping mid-label or between labels.

Calibration usually resolves these common label-feeding issues effectively.


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