formula to calculate days between two dates in salesforce - Salesforce lobe For You

Solution: If both dates are of date datatype,then directly subtract start date from end date field to get the number of days between 2 dates.

Example: Start Date and End Date are date fields on Lead Object.

The formula field (No.of days) will be like this 

Output:

If both are of datetime datatype fields,then also directly subtract start date time from end date time field to get the number of days between 2 dates.

Example: Start Date and time and End Date and Time are date time fields on Lead Object.

The formula field (No.of days) will be like this 

Output: