Cost of Poor Quality Calculator: Formula, Example & Instant Result
The cost of poor quality (COPQ) adds up what an organisation spends because things are not done right the first time β internal and external failures β together with what it spends on appraisal and prevention. Expressed as a share of revenue, it makes quality a business number.
β³ Values are pre-filled with an example β replace them with your own data.
Your data
$
Scrap, rework, downgrades found before delivery.
$
Returns, warranty, complaints found after delivery.
$
Inspection, testing, audits, measuring equipment.
$
Training, process design, planning, supplier development.
$
Result
Total cost of quality500,000 $
Sum of the four quality-cost categories for the period.
Share of revenue6.25%
How much of every unit of revenue goes to quality costs.
Failure-to-prevention ratio9.5 : 1
Every unit spent on prevention is matched by 9.5 units of failure cost.
Quality costs by category; total 500,000 $, which is 6.25% of revenue.
4Failure-to-prevention ratio = 380,000 / 40,000 = 9.5 : 1
What it means
Poor quality costs 6.25 % of revenue, and every unit spent on prevention is matched by 9.5 units of failure β most of them external, where customers see them. Shifting money into prevention usually pays back; the often-quoted 1:10:100 rule (a problem costs more the later it is found) is a rule of thumb, not a law, but the direction holds.
Tips & common mistakes
β²Include only real, recorded costs; estimate hidden costs (lost sales, overtime) separately and label them as estimates.
β²Appraisal is still a loss: inspection finds defects but does not prevent them.
β²Use the same period for all four categories and for revenue β usually one financial year.
β²Ask finance for scrap, warranty and returns accounts first; they usually exist even without a dedicated quality-cost study.
β²AI assistants may present 1:10:100 or similar ratios as facts; treat them as rules of thumb and use your own numbers.
AI prompt for this calculation
Paste it into your AI assistant to be walked through the calculation with your own data.
Act as a quality manager and help me calculate the cost of poor quality (COPQ) for my organisation.
Use exactly these formulas:
COPQ = internal failure + external failure + appraisal + prevention
COPQ % of revenue = COPQ / annual revenue Γ 100
Failure-to-prevention ratio = (internal + external failure) / prevention (if prevention is 0, say the ratio is undefined)
Rules:
1. Work step by step and keep the currency on every line.
2. Repeat my figures first and check the thousands and decimal separators.
3. If a category is missing, ask me β never fill it with an industry average.
4. Label any rule of thumb (such as 1:10:100) clearly as a rule of thumb, not a fact.
5. Suggest which category to reduce first and why.
My data (same period):
Internal failure =
External failure =
Appraisal =
Prevention =
Annual revenue =
Currency =
The buttons copy the prompt first, then open the assistant in a new tab.
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Next step Β· DOCAMIN
Turn this into a quality cost report for management review in DOCAMIN.
What are the four classic categories of quality costs?
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Prevention (training, planning, process design), appraisal (inspection, testing, audits), internal failure (scrap, rework, downgrades found before delivery) and external failure (returns, warranty, complaints, recalls found after delivery). The last two are the cost of poor quality in the narrow sense.
What is the difference between visible and hidden quality costs?
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Visible costs appear in the accounts β scrap, warranty, inspection wages. Hidden costs such as lost customers, extra inventory, expediting and management time are real but rarely recorded, so a calculated COPQ is usually a lower bound.
Why is appraisal counted as a cost of quality?
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Inspection and testing do not add value to the product; they exist because the process cannot yet be trusted to make it right every time. Better prevention usually allows less appraisal.
How do I get the numbers without a dedicated study?
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Start with what finance already tracks: scrap and rework accounts, warranty and returns, inspection and laboratory costs, training budgets. Use one financial year, note any estimates, and refine the categories in the next cycle.
Last tested: October 2026 Β· Tested with: automated math tests (3+ cases) Β· Reviewed by: Quality for Everyone editorial team
