# Manually change the formula

{% hint style="success" %}
To make this setting you must have access to the user interface. If this is not the case, see here how to do it:[access-to-the-user-interface](https://instruction.hydrom.io/readme/access-to-the-user-interface "mention")
{% endhint %}

There are many ways to calculate the formula of the hydrometer. When a formula has been calculated, it can be entered under ("Calibration" --> "Custom Form") and saved with the button below.

![](https://3744546148-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MgXIkSDi1JF7mP1grhN%2Fuploads%2Fgit-blob-4bd6378ecc6556c8574c637217f83431f74b7876%2FFolie46.png?alt=media)