How To Calculate Decline In Sales. But, if you have a thin 30% gross margin and you drop your prices 20%, you must triple your unit sales (i.e., increase unit sales 200%) to have the same gross profit dollars. Percentage decrease is calculated using the formula given below.
Sales = number of units sold * average selling price per unit. ∴ percent decrease = (decreased value / original value) × 100. Sales = $530,000,000 or $530 million.
