Record Counts in reports are great, but if you have a report with multiple objects, record counts won't always provide an accurate count of how many records from each object are queried in the report. For example, if we use a Report Type of Appointments with or without Sales, the Record Count will display the number of Appointments but there is no way to know the Total number of Sales.
For that, you need a unique Count field on each object. Follow the steps in this article to make a simple Count field that can be used in report summaries.
1. Go to Setup and navigate to the object you're adding a count to. Clickpath Setup>App Setup>Create>Objects then click your desired object (in this example: Sale).
2. On the object page, create a new custom field by pressing the "New" button on "Custom Fields and Relationships"
3. For Step 1 of field creation where it asks to pick the field Data type, select "Formula", click next, then fill out Step 2. Name the field something that makes sense, like "Sale Count" and put that in the "Field Label". Then pick a "Formula Return Type" of "Number" and specify '0' decimal places like pictured below, then click next:
4. On Step 3, put the number "1" in the big formula box, change nothing else and click next.
5. Click next until the end and hit save, changing nothing else.
6. Now that the field is created, you'll need to put it on your report. This won't be possible unless you add it to your report type. See this article for editing or creating report types: How To - Create Custom Report Types with Custom Fields