AQL (Acceptance Quality Limit) is the worst tolerable process average when a continuing series of lots is submitted for acceptance sampling. It is defined in ISO 2859-1 and represents the maximum percent defective considered acceptable as a process average.

How do I choose the right AQL value?

AQL values depend on the criticality of defects. Critical defects typically use AQL 0 (100% inspection). Major defects often use AQL 1.0 or 2.5. Minor defects may use AQL 4.0 or 6.5. The choice depends on the product and customer requirements.

What are inspection levels I, II, and III?

General inspection level II is the default. Level I uses smaller samples (less discrimination) and is used when less inspection is needed. Level III uses larger samples (more discrimination) for critical products requiring higher confidence. Inspection levels only select the sample size code letter — they are a separate concept from normal, tightened and reduced inspection, which are severities changed by the switching rules of ISO 2859-1.

What do Ac and Re numbers mean?

Ac (Accept number) is the maximum number of defectives allowed to accept the lot. Re (Reject number) is the minimum number of defectives that requires rejection. If defectives found ≤ Ac, accept the lot. If defectives ≥ Re, reject the lot.

What is the difference between normal, tightened, and reduced inspection?

Normal inspection is the default. If 2 out of 5 consecutive lots are rejected, switch to tightened inspection (lower Ac numbers). After 5 consecutive accepted lots under tightened, return to normal. Reduced inspection (smaller samples) is allowed after 10 consecutive lots accepted under normal with good quality.

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AQL 抽樣表

查詢 ISO 2859-1 抽樣計畫。輸入批量、檢查水準及 AQL 值，即可取得樣本量、接收數 (Ac) 與拒收數 (Re)。

ISO 2859-1ANSI/ASQ Z1.4正常檢查

抽樣計畫

樣本量

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接收數 (Ac)

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拒收數 (Re)

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樣本代碼字母

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AQL 抽樣流程

1. 確定批量 → 2. 選擇檢查水準 (預設：II) → 3. 查找樣本量代碼字母 → 4. 查詢您 AQL 值對應的 Ac/Re 數值 → 5. 檢查樣本 → 6. 若不良品 ≤ Ac → 接收批量。若不良品 ≥ Re → 拒收批量。

經驗法則： AQL 2.5 搭配水準 II 是製造業中最常用的組合。它在檢查成本與品質保證之間提供了良好的平衡。

等級與嚴重度： 檢查等級（S-1…S-4、I、II、III）僅用於選擇樣本大小代碼字母。正常、加嚴和減鬆檢查是另一種概念——根據 ISO 2859-1（第 9 條）的切換規則，基於最近的批次接收歷史所適用的檢查嚴重度。此計算器提供單次抽樣計畫的 正常檢查 （表 2-A）；當嚴重度切換時，檢查等級保持不變。

樣本大小代碼字母（II 級）

批量	代碼	樣本量
2–8	A	2
9–15	B	3
16–25	C	5
26–50	D	8
51–90	E	13
91–150	F	20
151–280	G	32
281–500	H	50
501–1200	J	80
1201–3200	K	125
3201–10000	L	200
10001–35000	M	315
35001–150000	N	500
150001–500000	P	800
500001+	Q	1250