What is Total Cost of Quality?
Total Cost of Quality (CoQ) is the full amount your business spends to prevent defects, inspect output, and deal with failures when quality breaks down.
It matters because these costs can quietly consume 10–20% of revenue, eroding gross margin, EBITDA, and ultimately the value you create for shareholders.
Formula
The core relationship:
Split into “good” vs “poor” quality:
Where:
As a share of top line:
Optional per-unit lens:
Example
A manufacturer reports:
- Prevention costs: $45,000
- Appraisal costs: $32,000
- Internal failure costs: $28,000
- External failure costs: $42,000
- Revenue: $1,200,000
- Units delivered: 52,000
Cost of good quality:
Cost of poor quality:
Total cost of quality:
Quality cost as % of revenue:
Quality cost per unit:
The calculator would flag that 12.3% of revenue is being spent on quality; management can then test scenarios (e.g., shifting more into prevention) to see how much CoQ could be reduced and how much margin and economic profit that would unlock.