What are the 4 costs of quality?

Prevention costs (avoiding defects), appraisal costs (inspecting and testing for defects), internal failure costs (scrap and rework caught before shipping), and external failure costs (returns, warranty, recalls, and lost business after defects reach the customer). The categories were defined by Armand Feigenbaum in his 1956 Harvard Business Review article "Total Quality Control."

What is the 1-10-100 rule in quality?

A rule of thumb popularized by George Labovitz and Yu Sang Chang in Making Quality Work (1992): a defect costs about $1 to prevent, $10 to correct when caught internally, and $100 once it reaches the customer. The exact ratios vary by industry; the escalating shape is what matters.

What is the difference between cost of quality and cost of poor quality?

Cost of quality (COQ) includes all four categories: prevention, appraisal, internal failure, and external failure. Cost of poor quality (COPQ) refers only to the failure categories, the money lost because defects occurred. Prevention and appraisal are sometimes called the cost of good quality.

What percentage of sales is cost of quality?

ASQ reports quality costs commonly run 15-20% of sales revenue and can reach 40% of operations in some organizations, with wide variation by industry and maturity. The reliable finding is directional: failure costs are usually several times larger than prevention spending, and most of them are hidden in routine accounts.

Is cost of quality the cost of the quality department?

No, and this is the most common misreading. The quality department's budget is mostly appraisal and prevention cost; the bulk of COQ is failure cost scattered across scrap accounts, rework overtime, expedited freight, credits, and downtime. Measuring COQ usually reveals quality is underfunded, not overfunded.

Cost of Quality: Prevention, Appraisal, and the Price of Getting It Wrong

Cost of quality (COQ) is the total cost a company pays because quality cannot be taken for granted: the money spent preventing defects, the money spent inspecting for them, and the money lost to the defects that happen anyway. It is conventionally split into four categories: prevention, appraisal, internal failure, and external failure.

The idea has a long pedigree. Joseph Juran introduced the concept in his 1951 Quality Control Handbook, describing avoidable quality losses as "gold in the mine" waiting to be recovered. Armand Feigenbaum's 1956 Harvard Business Review article "Total Quality Control" defined the four cost categories still used today. The framework is old because it works: it turns "quality" from a virtue into a line item a plant manager can act on.

What Is Prevention Cost?

Prevention cost is the money spent to keep defects from occurring in the first place, before anything is made wrong. It includes quality planning, process design and capability work, error-proofing devices (poka-yoke), supplier qualification, preventive maintenance done for quality reasons, and training. Prevention is the smallest budget line in most plants and the highest-return one: every dollar here reduces spending in the other three categories.

What are the four costs of quality?

The four categories form a simple framework. The first two are costs you choose; the last two are costs that choose you.

Prevention costs, spent so defects never occur: quality planning, error-proofing, training, supplier qualification, process capability studies.
Appraisal costs, spent finding defects: incoming inspection, in-process checks, final inspection, test equipment and its calibration, audits.
Internal failure costs, paid when defects are caught before shipping: scrap, rework, re-inspection, downtime from quality stops, downgrading product to seconds.
External failure costs, paid when defects reach the customer: returns, warranty claims, complaints handling, recalls, chargebacks, and the hardest one to book, lost future business.

The COQ quadrant. Prevention and appraisal are chosen costs; internal and external failure are imposed ones.

How big is the cost of quality?

Bigger than most P&Ls admit, because failure costs hide in scrap accounts, overtime, expedited freight, and "the way we've always run." The American Society for Quality notes that quality costs commonly run 15-20% of sales revenue, and can go as high as 40% of total operations in some organizations (ASQ, Cost of Quality). Even if your plant is well below those figures, COQ is almost always a multiple of what the quality department costs, which is the point: quality is not the expense; failure is.

What is the 1-10-100 rule?

The 1-10-100 rule is a rule of thumb about cost escalation: a defect that costs $1 to prevent costs roughly $10 to correct when caught internally and $100 when it reaches the customer. It was popularized by George Labovitz and Yu Sang Chang in their 1992 book Making Quality Work, and a related finding appears in Barry Boehm's 1970s software engineering research on how defect cost grows the later a defect is found.

Treat the numbers as a shape, not an accounting law. The exact ratios vary by industry, but the exponential escalation is consistent: fixing a mislabeled pallet in the warehouse costs a relabel; fixing it at a customer's DC costs chargebacks, freight, and an uncomfortable phone call; fixing it after a recall notice costs more than the product ever earned.

How do you start measuring COQ with data you already have?

You do not need a new accounting system. Most plants can build a credible first COQ estimate in a week from existing records:

Internal failure: scrap transactions and rework hours from production records, quality-caused downtime from your downtime log, re-inspection time.
External failure: credits, returns, and chargebacks from the ERP; complaint handling time; warranty spend.
Appraisal: inspection and lab headcount, calibration contracts, testing consumables.
Prevention: training hours, error-proofing projects, supplier audits, quality planning time.

Then put the failure costs on a Pareto chart by cause. The first pass will be imperfect; it will still show the same thing it shows nearly everywhere, that failure costs dwarf prevention spending and a handful of causes drive most of the loss. That chart is your improvement agenda.

The practical obstacle is usually data capture, not math. If quality checks, holds, and scrap reasons live on paper forms, the numbers cannot be assembled without weeks of transcription, which is why they never are. Digitizing those records at the station, the way Harmony's paperwork digitization and quality intelligence modules do, makes COQ a report you can pull rather than a project you dread, and modern QMS software can then track the categories continuously.

One caution on strategy: the goal is not zero appraisal or maximal prevention spending. The goal is shifting spend leftward, from failure toward prevention, until the total curve stops falling. Every plant that has done this seriously has found the early prevention investments pay for themselves quickly; Juran's gold in the mine is usually still there.