You can have 10 roll up summaries fileds.. Additional Custom Field Limits
The number of custom fields allowed per object varies according to your Salesforce Edition. The maximum number of activities, long text area fields, rich text area fields, relationship fields, and roll-up summary fields varies as well. The following table shows the maximum limits for each custom field type and edition.
Custom Field Limits Personal Edition Contact Manager GroupEdition Professional Edition Enterprise Edition Developer Edition Unlimited Edition Activities No additional limit No additional limit No additional limit 20 100 100 100 Long Text Area Fields
There are no limits to the number of rich text area and long text area fields that an object can contain, although your Edition's limit for the total number of custom fields allowed on an object, regardless of field type, applies. Each object can contain a total of 1.6 million characters across long text area and rich text area fields. The default character limit for long text area and rich text area fields is 32,768 characters. A long text area or rich text area field needs to contain at least 256 characters.
Rich Text Area Fields Relationship Fields No additional limit 25 25 25 25 25 25 Roll-up Summary Fields No additional limit 10 10 10 10 10 10
