Skip to content 
EN 
DE 
العربية 
Quality Control (QC): What It Is, and How It Differs from Quality Assurance
Quality control is the checking that catches defects in the product: inspection, testing and measurement against spec. It’s the detection half of quality. Quality assurance is the other half, the process work that stops defects being made in the first place. QC finds them; QA prevents them.
Why is quality control important?
Quality control matters because it catches defects before they reach the customer, protecting both product reliability and the company’s reputation. Consistent inspection, testing and measurement keep scrap, rework and warranty costs down and give clear evidence that a product meets specification. Alongside quality assurance, it is the part of a quality management system that most directly affects what actually ships.
What methods does quality control use?
QC is hands-on and product-facing:
- Inspection against the drawing, dimensional and visual.
- Functional and performance testing of the finished item.
- Sampling and statistical process control to catch drift before it becomes scrap.
- Gauging and measurement, with calibrated instruments.
- Nonconformity handling, so a bad part doesn’t reach the customer.
How does QC differ from QA?
Detection versus prevention. QC inspects the product to catch defects that already exist; quality assurance builds the process so fewer are made. QC is reactive and product-specific; QA is proactive and system-wide. Lean on QC alone and you inspect quality in, one part at a time, instead of building it.
QC vs QA at a glance
Catching defects versus preventing them.
| Aspect | Quality Control (QC) | Quality Assurance (QA) |
|---|---|---|
| Goal | Catch defects | Prevent defects |
| Focus | The product | The process |
| Timing | After the fact | Before and during |
| Nature | Reactive, sample-based | Proactive, system-wide |
Free Quality Control Inspection Checklist
It walks the dimensional, visual and functional checks with pass, fail and a nonconformity log, so defects get caught and recorded. Download the checklist (PDF). You can also complete the checklist digitally in flowdit on your phone, tablet or PC.
Related Terms
- Control Chart – a core QC tool.
- Visual Inspection – a common QC method.
- First Article Inspection (FAI) – QC on the first part.
- Total Quality Management (TQM)
Further Reading
- Quality control audits: purpose, process, impact
- QMS-Software – digital quality management
