[header] How to calculate gross profit margin and net profit margin [title] Calculate total sales. [step] Add up all the money made from the sale of goods and services sold by your business. This is the total sales. 
You don't necessarily have to calculate your revenue for your business as a whole-depending on your specific needs, you may want to find the revenue for individual departments of your business or for individual products. Total sales can be calculated as number of units sold multiplied by selling price per unit.