# How do I calibrate the humidity sensor?

However, if you notice slight variations, calibration can help fine-tune accuracy.

### W**hy not use the salt test?**

While the salt test is a common DIY method, it’s notoriously unreliable and difficult to execute precisely. 

An inaccurate reference point can lead to incorrect calibration - which may be worse than no calibration at all.

Instead, we recommend using a [Boveda One-Step Hygrometer Calibration Kit](https://store.bovedainc.com/products/calibration-kit) for the most precise and repeatable results.

### H**ow to calibrate humidity using a Boveda kit**

{% stepper %}
{% step %}
**Place your Grow Sensor inside the calibration bag** 

Use a Boveda 75% One-Step Hygrometer Calibration Kit, which can be found online for under £10.
{% endstep %}

{% step %}
**Seal the bag and leave it undisturbed for 48–72 hours** 

Keep it in a stable environment with minimal temperature fluctuations.
{% endstep %}

{% step %}
**Adjust the calibration in the app** 

If the reading is slightly off, use the app’s calibration settings to fine-tune it to 75.0% RH.
{% endstep %}
{% endstepper %}

{% hint style="info" %}
**Pro Tip:** Keep your calibration kit sealed when not in use. It can be reused for at least three months to re-verify accuracy.
{% endhint %}

### **Important notes**

* **Only calibrate if necessary** – The Grow Sensor is highly accurate out of the box. Adjustments should only be made if a verified reference shows a discrepancy.
* **Make small adjustments** – Calibration is intended to correct minor variations (typically within ±5% RH). If your readings are significantly off, there may be an issue with the calibration process or sensor.
* **Temperature and humidity calibrations are separate** – You can calibrate one or both independently, depending on what’s needed.

If you're seeing large discrepancies or need help calibrating, contact us at <support@growsensor.co> we’re happy to help!


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