How To Calculate Fixed Cost. One way is to simply tally all of your fixed costs add them up and you have your total fixed costs. I Found This Formulae Very Helpful It Shoes Four Different Ways Of Calculating Degree Of Operating Leverag Contribution Margin Financial Management Fixed Cost How per-item cost affects production costs and manufacturing costs differently. . To calculate this number you need to understand and calculate both your fixed costs and variable cost per unit. The division method is useful if you only want to determine how your fixed costs affect the fixed cost per unit. A class of 25 students took a science test. To calculate COGS business owners need to determine the value of their inventory at the beginning and end of every tax year. They offer a 2 discount if the customer pays with cash. Tallying your fixed costs will tell you what it costs to run your business. Meanwhile variable cost...