Quick answer
Divide labor cost by net sales for the same period and multiply by 100. With $840 in labor costs and $3,500 in net sales, labor costs are 24% of sales.
Formula and assumptions
Labor percentage = 100 × labor cost ÷ net sales. Target labor cost = net sales × target percent ÷ 100.
Worked example
A labor cost of 300 on net sales of 1,000 is 30%.