# AQL applied to the batch record.

"Inspecting less" can't be improvised: it takes a standardized, auditable framework. The **AQL** (acceptable quality level) is one: it sizes the sampling and lets the **inspection breathe** — reduced when the history is good, tightened when it degrades. Enough to streamline the batch record at the right level of risk, without giving anything up on compliance.

Normal · Reduced · Tightened

The three AQL regimes: inspection adjusts automatically to the quality demonstrated over time, instead of staying frozen.

Principle of AQL sampling plans (ISO 2859 standard for attribute inspection).

The **AQL** defines, for a given lot size and target quality level, how many units to draw and the acceptance / rejection threshold (Ac/Re). Its strength: **switching rules**. A compliant history switches you to **reduced inspection** (you draw fewer units); a degradation triggers **tightened inspection**. Inspection becomes proportionate and self-regulating — exactly what you want to streamline a batch record without losing control.

Frozen sampling never rewards quality.

When the sample size and frequency never change, an exemplary supplier or process is inspected exactly like a poor one. It's discouraging, costly and has no risk logic. AQL fixes this: it ties the inspection effort to the performance actually demonstrated, in both directions.

## Three regimes, switching rules.

Normal

### The default regime

The standard plan as long as quality is compliant but without enough history to streamline.

Reduced

### The reward for consistency

After a series of compliant lots, you draw fewer units: this is where the workload reduction is won.

Tightened

### The safety net

As soon as quality degrades, you automatically tighten up. Streamlining is never a one-way street.

For each plan: a sample size and an acceptance / rejection pair (Ac/Re). The switch between regimes follows rules defined in advance — that's what makes the streamlining defensible in an inspection.

## From the AQL principle to real frequency.

AQL applies above all to attribute inspection (compliant / non-compliant). Used well, it structures the streamlining.

### Tie it to real risk

The regime (normal / reduced / tightened) follows from the deviation history and criticality — not from an arbitrary decision.

### Document the switch

The rules for moving from one regime to another are written into the procedure: traceable and auditable.

### Combine with variable inspection

For measured parameters (weight, volume…), AQL is complemented by process capability (Cpk) and history.

### Plan for the rollback

A degradation criterion immediately brings you back to the higher regime: streamlining stays under control.

## Proportion it, always.

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### Streamline IPC

The method for which AQL is the 5th step.

Read →](/en/blog/streamline-in-process-controls-ipc/)[

### Process capability (Cpk)

The statistical proof on the measured-parameters side.

Read →](/en/blog/process-capability-cpk-streamline-controls/)[

### Delegate to the supplier

AQL also structures incoming inspection.

Read →](/en/blog/delegate-controls-supplier-coa/)

## AQL, in plain terms.

What is the AQL? +

The AQL (acceptable quality level) is the level of defects deemed acceptable for a lot. It underpins sampling plans (ISO 2859 standard for attribute inspection): for a given lot size, it sets the sample size and the acceptance / rejection threshold (Ac/Re).

What do normal, reduced and tightened inspection mean? +

These are the three AQL regimes. Normal inspection is the default regime; reduced inspection draws fewer units after a series of compliant lots; tightened inspection ratchets up as soon as quality degrades. Predefined switching rules move you from one to another.

Does AQL let you streamline inspection? +

Yes: switching to reduced inspection is precisely the mechanism that reduces the workload, while keeping a safety net (return to tightened). It's a standardized framework, and therefore defensible in an inspection, provided you document the switching rules and the link to the quality history.

AQL for attributes, Cpk for measurements? +

In practice, yes: AQL structures attribute inspection (compliant / non-compliant), while process capability (Cpk) and history justify streamlining inspection on measured parameters (weight, volume…). The two combine within an overall approach.

## Let your controls breathe.

Let's structure your AQL sampling plans to streamline at the right level of risk, with documented switching rules.