Convert 15 character IDs to 18 character IDs in formula field

Hi ,

We have new method "CASESAFEID()"in formula field now to make 15 character Id to 18 character.

Classic

1. Go to Setup | Customize | object name | click Fields

a. For Custom objects: Setup | Create | Objects | object name

3. In the related list "Custom Fields & Relationships" click New.
4. Click the Formula radio button.
5. Click the Text radio button for 'Formula Return Type.'
6. Input the following Formula into the Formula Editor:

CASESAFEID(Id)

7. Set Field Visibility, add or remove from the page layout.
 8. Click Save.

Lightning
 

1. Go to Setup | Object Manager | Object name | Fields & Relationships
2. Click New.
3. Click the Formula radio button.
4. Click the Text radio button for 'Formula Return Type.'
5. Input the following formula into the Formula Editor:

CASESAFEID(Id)

6. Set Field Visibility, add or remove from the page layout.
7. Click Save.

Reference:

https://help.salesforce.com/articleView?id=000005288&language=en_US&type=1