outofspec

Out of specification, often abbreviated as out of spec or OOS, describes a measurement, test result, or product that falls outside predefined acceptance criteria or specifications. It is a quality problem flag used across industries to indicate that something does not meet the required tolerances, performance, or compliance standards.

The concept is applied in many sectors, including manufacturing, pharmaceuticals, electronics, food and beverage, and automotive. Spec limits are typically defined by upper and lower bounds or a target value with tolerance. A result outside these limits is considered out of spec and may trigger an investigation, containment, and corrective action.

Causes of out-of-spec results can include measurement errors, instrument calibration drift, defective materials, process variation, environmental factors, human error, and sampling or data recording issues. Distinguishing true nonconformances from transient or erroneous readings often requires retesting or verification using qualified methods and metrology practices, such as measurement system analysis.

Handling out-of-spec results involves containment to prevent distribution of nonconforming products, documentation in deviation reports, and root cause analysis. Disposition options range from rework, repair, or adjustment to scrapping or returning material, depending on risk and feasibility. Regulatory and quality systems commonly require formal CAPA processes, traceability, and trend analysis, with standards such as ISO 9001 and GMP guiding the investigation and corrective actions. In pharmaceutical contexts, the terms out of specification (OOS) and out of tolerance (OOT) are frequently used to distinguish different compliance aspects.

Overall, managing out-of-spec results aims to protect safety, performance, and compliance while minimizing disruption and cost.