Custom field type conversion
Key Takeaway
Converting a custom field that already holds data can cause data loss, so the safest approach is to convert only custom fields that have no data yet.
You can change the data type of an existing custom field, for example from Text to Text Area (Long), without deleting and recreating it. Many conversions delete or cut off existing data, and some fields cannot be converted at all. You need to know which changes are safe before you make them.
How to change a custom field's type
You need the "Customize Application" permission to change a custom field's type. You can make the change in both Salesforce Classic and Lightning Experience.
Before you change a field's type, make sure it isn't the target of a workflow field update. Also check that no field update formula references it in a way the new type would make invalid.
- From the object's management settings, go to "Fields".
- Click "Edit" next to the custom field.
- Click "Change Field Type".
- Pick the new data type, and click "Next".
- Enter the label, name and other attributes.
- Save.