I recently observed the jewelry industry, and the calculation formula of processing loss is rather confusing. Give you a standard calculation formula, which you can apply according to the actual loss rate. The weight of finished product is 18K 100g, and the loss rate is 15%. The formula is100 ÷ (1-15%). When the percentage is converted into decimal, the formula is:100 ÷ (1-0.15) =100 ÷ 0.85 =117.647g.