How many custom fields in Zoho CRM is dependent on two factors. Firstly it depends on which Edition you are using:
Free Edition: No custom fields
Stand Edition: 10 fields per module
Professional Edition: 155 fields per module (Note: Activities module has only 140 fields)
Enterprise Edition: 310 fields per module (Note: Activities module has only 230 fields)
Then it depends on the age of your instance of CRM. Some customers have what is called "Old Professional" or "Old Enterprise" these are editions where Zoho maintained the price at time of a price increase but didn't enhance the feature set within the CRM.
The other issue to consider is the type of custom field in Zoho CRM as there are individual limits on each of the field types. So for example the limit on Lookup fields is 5 per module, Checkbox is 50, etc. Attached is an example of the field limitations within Zoho CRM utilised in Zoho One.
The best advice is to get in touch as these limits do change, but we have also devised some workarounds for customers who have reached the ceiling of a particular field type.
Published: May 2019