How to Calculate AQL Sample Size: Tables, Ac/Re Numbers & Real Examples

Published: 2026-08-10 Dony

Sample of 200. AQL 2. 5. Accept at 10, reject at 11. That's the whole answer for most importers. Here's how to get it yourself in 60 seconds — no engineering degree required.

Sample of 200. AQL 2.5. Accept at 10, reject at 11.

That's the whole answer for most importers. Here's how to get it yourself in 60 seconds — no engineering degree required.

Every importer who orders from China eventually asks: "How many units do I actually need to check?"

The answer isn't a percentage. It's a table — ANSI/ASQ Z1.4, the standard behind AQL sampling. Read it right and you know exactly how many units to inspect and how many defects are allowed before the batch fails.

The AQL Calculation in 3 Steps

Step 1: Find your lot size — the total number of units in the shipment.

Step 2: Read across to your inspection level — most importers use level II (normal). That gives you a sample size code letter (A through R).

Step 3: Read the sample size and Ac/Re numbers — from your code letter across to your AQL column (1.0, 2.5, 4.0...). Ac = maximum defects allowed to pass. Re = defects that fail the batch.

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The Sample Size Table (Level II, ANSI Z1.4)

Lot size	Code letter	Sample size	AQL 1.0 (Ac/Re)	AQL 2.5 (Ac/Re)	AQL 4.0 (Ac/Re)
51 – 90	E	13	0 / 1	1 / 2	1 / 2
91 – 150	F	20	0 / 1	1 / 2	2 / 3
151 – 280	G	32	0 / 1	2 / 3	3 / 4
281 – 500	H	50	1 / 2	3 / 4	5 / 6
501 – 1,200	J	80	1 / 2	5 / 6	7 / 8
1,201 – 3,200	K	125	2 / 3	7 / 8	10 / 11
3,201 – 10,000	L	200	5 / 6	10 / 11	14 / 15
10,001 – 35,000	M	315	7 / 8	14 / 15	21 / 22
35,001 – 150,000	N	500	10 / 11	21 / 22	21 / 22
150,001 – 500,000	P	800	14 / 15	21 / 22	21 / 22

Values per ANSI/ASQ Z1.4 single sampling, general inspection level II. The highlighted row covers most FBA orders (3,201–10,000 units).

Three Real Examples

Example 1: 5,000 phone cases, AQL 2.5

Lot 5,000 → code L → sample 200 units. At AQL 2.5: accept at ≤10 defects, reject at ≥11. 💰 If your inspector finds 12 defective units, the batch fails — even if the factory says "it's only 0.6%".

Example 2: 800 ceramic mugs, AQL 1.0 (stricter)

Lot 800 → code J → sample 80 units. At AQL 1.0: accept at ≤1 defect, reject at ≥2. ⚠️ For fragile items with a strict buyer, AQL 1.0 is the right call.

Example 3: 25,000 LED bulbs, AQL 4.0

Lot 25,000 → code M → sample 315 units. At AQL 4.0: accept at ≤21 defects, reject at ≥22. AQL 4.0 is the loosest common standard — fine for cosmetic categories, risky for electronics.

Common Mistakes Importers Make

❌ Inspecting a fixed 10%. A 10% sample is not AQL. The table decides, not a percentage.
❌ Using the wrong AQL for the category. Electronics at AQL 4.0 lets too many failures through. Use 1.0–2.5 for functional products.
❌ Forgetting critical defects. Critical defects (safety, legality, wrong product) are always AQL 0 — one critical defect fails the lot regardless of Ac.
❌ Counting defects instead of defective units. AQL counts units with defects. One unit with three defects is one defective unit.

Real inspection: when "the sample was perfect" wasn't enough

A seller ordered 6,000 portable chargers from a new factory. The hand sample worked flawlessly. They skipped inspection and released the balance.

We tested 200 units on the next order. ❌ 14 units failed — 7 with dead batteries, 5 with loose USB ports, 2 with no output at all. At AQL 2.5 the limit was 10. The batch failed, and the factory agreed to sort and rework before shipping. 💰 The inspection cost $169. The alternative was a $9,000 batch of dead power banks landing at FBA.

That's the whole argument for AQL sampling: it's not about catching every defect. It's about knowing — with statistical confidence — whether the batch is good enough to ship.

Frequently asked questions

What is the AQL calculation formula?
There is no single formula — AQL uses the ANSI/ASQ Z1.4 table. Find your lot size row, read across to your inspection level to get the sample size code, then read that code across the AQL column for your Ac/Re numbers. For a 3,201–10,000 unit lot at level II: sample 200 units; at AQL 2.5, accept at 10, reject at 11.

How many units should I inspect for a 5,000-unit order?
At level II, a 5,000-unit lot (code L) requires a sample of 200 units. At AQL 2.5, the batch passes with ≤10 defective units and fails with ≥11.

What is the difference between AQL 1.0, 2.5, and 4.0?
Lower AQL numbers are stricter. AQL 1.0 allows the fewest defects (e.g., 200-unit sample: pass at ≤5), AQL 2.5 allows more (pass at ≤10), and AQL 4.0 allows the most (pass at ≤14).

Does CloudSpects do the AQL calculation for me?
Yes. Every inspection uses the correct sample size and AQL level based on your order size and product type. You get a clear pass/fail decision with photos of every defect. From $169 per man-day.

Can I use the AQL calculator for free?
Yes — the free AQL calculator gives you sample size and Ac/Re numbers in seconds, no login needed.

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