Calculate prevention, appraisal, internal failure, and external failure costs with quality cost ratio and trend analysis.
A defect costs little to prevent, more to catch, and the most to reach a customer. This tool takes the quality spending you enter - prevention, appraisal, internal failure, and external failure - totals the four into a cost of quality, divides by your sales to get a quality cost ratio, and lays the periods side by side so you can watch the trend. The number that most users are surprised by is the size: quality costs of 10% or more of sales are common, and the spending mix - not the total - is usually the actionable signal.
A concrete input and expected output from the current implementation.
Input
Quarter 1: prevention 30,000; appraisal 20,000; internal failure 70,000; external failure 80,000; sales 2,000,000. Quarter 2: prevention 45,000; appraisal 30,000; internal failure 50,000; external failure 55,000; sales 2,000,000.
Expected output
Total cost of quality: Q1 $200,000 (10.0% of sales), Q2 $180,000 (9.0% of sales). Ratio fell 1.0 percentage point; prevention and appraisal rose from 25% to 42% of total quality cost while failure costs fell.
The sales base is the same $2,000,000 in both periods, so the fall from 10.0% to 9.0% is real improvement, not a revenue artifact. Q2 spent more up front on prevention and appraisal (42% of the total versus 25%) and the failure buckets shrank by $45,000.
Prevention covers planning, training, and process control; appraisal covers inspection, testing, and audits; internal failure covers scrap, rework, and downtime found before shipment; external failure covers warranty, returns, and recalls after it. The tool sums what you enter in each bucket and shows each category's share of the total, so a dominant bucket is visible at a glance.
Each period's total is divided by the sales figure you give it, producing a percentage. Enter several periods and the tool aligns them side by side to show whether the ratio is rising or falling, and which category is moving. Because the ratio divides by sales, a revenue dip inflates the ratio even if quality spending is unchanged, so trend views are only comparable when the sales basis stays consistent.
There is no single standard target. Widely cited figures put total cost of quality at 10-25% of sales for many organizations, with well-run programs reaching the low single digits, but the range depends on industry and on what a company chooses to count. Your own trend is the defensible number; treat published benchmarks as context, not a target.
Only if you estimate the value and enter it as an external failure cost, because a lost customer leaves no invoice line to read from the books. Most teams run the tool on recorded costs first, then add an explicit lost-business estimate in a separate scenario so the two never get mixed.
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