U.S. Code of Federal Regulations

Regulations most recently checked for updates: Aug 14, 2022

§ 43.106 - Choosing AQL's and sampling plans.

(a) The selection of AQL's and sampling plans for given lot sizes depends on too many factors to permit the issuance of a “pre-selected” standard set of plans for specified lot sizes. Each user of the standards of this subpart should select AQL's and sampling plans that are tailored to best meet his needs.

(b) Some of the factors that must be considered prior to selecting the AQL's are:

(1) Class of defects such as major and minor: Major defects would generally require lower AQL's than those for minor defects;

(2) Process capabilities under good commercial practice with respect to the defects in question: For example, if under normal production processes, the defect level cannot be kept below 2.0 percent defective, the selection of an AQL of 0.15 percent defective, although desirable for the defects in question, may not be practical;

(3) Consumer preferences: These may require higher AQL's or permit lower AQL's than process capabilities would indicate; and

(4) Time and cost required to sample and inspect a lot under various AQL's: The smaller the AQL the more time and cost of inspection.

(c) Some of the factors that may be considered prior to selecting the sampling plans for given lot sizes are:

(1) The applicable AQL(s): The AQL dictates, among other things, the smallest sample size that can be used and the size of the “jumps” from one sample size to the next larger one;

(2) The relative ability of the plans to discriminate between “good” and “bad” lots: Although several plans in these standards have the same AQL, they differ in their ability to reject lots worse than the AQL's. The OC curve in the standards of this subpart provide the basis for determining the discriminating ability of each plan;

(3) The amount, time, and cost of sampling required;

(4) The size and value of the lots relative to the producer and consumer protection a sampling plan affords: One may be willing to take larger risks of passing “bad” lots that are small or of lesser value than they would for larger more valuable lots;

(5) The knowledge about the lot(s) to be submitted for inspection: Lots consisting of product produced under essentially the same conditions may require smaller sample sizes than those consisting of product produced by different shifts and different raw stock for example; and

(6) The record of the quality level of previously submitted lots: The sample size can be smaller for lots submitted from a supplier with a consistent record of quality levels significantly better than the specified AQL(s) than sample sizes for the supplier whose records show considerable variability in quality, “borderline” supplies or product worse than the AQL.

Master Table of Single and Double Sampling Plans 1

Sample size code letter Sample size Acceptable quality levels
0.065 0.10 0.15 0.25 0.40 0.65 1.0 1.5 2.5 4.0 5.0 6.5 8.5 10.0 12.5 15.0
Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re
AAn1=1 0 1
An1=2 0 1
Bn1=3 0 1 0 3 1 2
nt=8 2 3
Cn1=4 0 1 1 2
Dn1=5 0 1 1 2
En1=6 1 22 3
EEn1=7 2 3
Fn1=9 0 1 1 2 2 3 3 4
Gn1=11 1 2 2 3 3 4
Hn1=13 0 1 2 3 3 4 4 5
Jn1=21 0 1 0 2 0 2 2 3 1 4 3 4 3 5 4 5 5 6 6 7
nt=31 1 2 2 3 3 4 5 6
Kn1=29 0 1 0 2 1 2 2 3 1 4 3 4 4 5 3 7 5 6 6 7 7 8
nt=65 1 2 6 7 9 10
Ln1=48 0 1 0 2 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 10 11 11 12
nt=72 1 2
Mn1=84 0 1 0 2 0 3 2 3 3 4 4 5 6 7 7 8 9 10 11 12 13 14 15 16 18 19
nt=120 1 2
nt=132 2 3
Nn1=126 0 1 0 2 0 3 2 3 3 4 4 5 6 7 9 10 10 11 13 14 16 17 18 19 22 23 26 27
nt=180 1 2
nt=210 2 3
Pn1=200 0 1 0 2 0 3 2 3 3 4 4 5 6 7 9 10 13 14 15 16 19 20 24 25 27 28 33 34 39 40
nt=284 1 2
nt=326 2 3
Qn1=315 0 1 0 2 0 2 3 3 4 4 5 6 7 8 9 13 14 19 20 22 23 28 29 35 36 41 42 50 51 59 60
nt=435 1 2
nt=519 2 3
Rn1=500 0 2 0 3 2 3 3 4 4 5 6 7 9 10 12 13 18 19 28 29 33 34 42 43 53 54 62 63 76 77 90 91
nt=644 1 2
nt=836 2 3
Sn1=800 0 3 2 3 3 4 4 5 6 7 9 10 13 14 18 19 27 28 42 4350 510 64 65 82 83 95 96117 118140 141
nt=1304 2 3
Tn1=1250 2 3 3 4 4 5 6 7 9 10 13 14 19 20 26 27 41 42 63 64 76 77
Un1=2000 3 4 4 5 6 7 9 10 13 14 19 20 28 29 39 40 62 63 96 97

1 Double plans are indicated by 2 sample sizes, n1 (first) and nt (total). Ac=Acceptance number Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.065 Percent Defective (or AQL=0.065 Defects per Hundred Units)

[Sampling plans - AQL=0.065]

Comparable sampling plans Identification letter of OC curve
Q R S, T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single31501624121250232,0003
Double5000280003
64412130423

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.10 Percent Defective (or AQL=0.10 Defects per Hundred Units)

[Sampling plans - AQL=0.10]

Comparable sampling plans Identification letter of OC curve
P Q R, S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single2000140812800231,250342,0004
Double3150250003
4351283623

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.15 Percent Defective (or AQL=0.15 Defects per Hundred Units)

[Sampling plans - AQL=0.15]

Comparable sampling plans Identification letter of OC curve
N P Q R, S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single126012641250023800341,250452,00067
Double2000231503
2841251923

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.25 Defects per Hundred Units

[Sampling plans - AQL=0.25]

Comparable sampling plans Identification letter of OC curve
M N P, Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single8401168123152350034800451250672000910
Double1260220003
1801232623

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.40 Percent Defective (or AQL=0.40 Defects per Hundred Units)

[Sampling plans - AQL=0.40]

Comparable sampling plans Identification letter of OC curve
L M N, P Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single48011081220023315345004580067125091020001310
Double840212603
1201221023

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.65 Percent Defective (or AQL=0.65 Defects per Hundred Units)

[Sampling plans - AQL=0.65]

Comparable sampling plans Identification letter of OC curve
K L M, N P Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single29016612126232003431545500678009101250131420001920
Double48028403
721213223

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=1.0 Percent Defective (or AQL=1.0 Defects per Hundred Units)

[Sampling plans - AQL=1.0]

Comparable sampling plans Identification letter of OC curve
J K, L M N P
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single2101481284231263420045
Double2902
6512
Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single3156750091080013141250192020002829

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=1.5 Percent Defective (or AQL=1.5 Defects per Hundred Units)

[Sampling plans - AQL=1.5]

Comparable sampling plans Identification letter of OC curve
H J, K L M N P
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single13012912482384341264520067
Double2102
3112
Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single31589500121380018191,25026272,0003940

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=2.5 Percent Defective (or AQL=2.5 Defects per Hundred Units)

[Sampling plans - AQL=2.5]

Comparable sampling plans Identification letter of OC curve
F J, K L M N P
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single90129234834844512667200910
Double2102
3123
Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single3151314500181980027281,25041422,0006263

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=4.0 Percent Defective (or AQL=4.0 Defects per Hundred Units)

[Sampling plans - AQL=4.0]

Comparable sampling plans Identification letter of OC curve
D G J K L M N
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single5011112212348458467126910
Double2914
6567
P Q R S T U
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single200131431519205002829800424312506364200096

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=5.0 Percent Defective (or AQL=5.0 Defects per Hundred Units)

[Sampling plans - AQL=5.0]

Comparable sampling plans Identification letter of OC curve
C F J, K L M N
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single4011122934485684781261011
Double2114
3134
P Q R S T
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single200151631522235003334800505112507677

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=6.5 Percent Defective (or AQL=6.5 Defects per Hundred Units)

[Sampling plans - AQL=6.5]

Comparable sampling plans Identification letter of OC curve
B E H J K L
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single3016121323213429454867
M N P Q R S
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single8491012613142001920315282950042438006465

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=8.5 Percent Defective (or AQL=8.5 Defects per Hundred Units)

[Sampling plans - AQL=8.5]

Comparable sampling plans Identification letter of OC curve
D G J K, L M
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single51211232445487884111
Double21352937
315665910
N P Q R S
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single12616172002425315353650053548008283

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=10.0 Percent Defective (or AQL=10.0 Defects per Hundred Units)

[Sampling plans - AQL=10.0]

Comparable sampling plans Identification letter of OC curve
A C F H J K L
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single2014129231334214529564889
M N P Q R S
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single84131412618192002728315414250062638009596

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristics (OC) Curves for AQL=12.5 Percent Defective (or AQL=12.5 Defects per Hundred Units)

[Sampling plans - AQL=12.5]

Identification letter of OC curve Comparable sampling plans
B, EE G J K L M
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single723113421562967481011841516
Double303
823
N P Q R S
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single1262223200333431550515007677800117118

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.

Sampling Plans and Operating Characteristic (OC) Curves for AQL=15.0 Percent Defective (or AQL=15.0 Defects per Hundred Units)

[Sampling plans - AQL=15.0]

Comparable sampling plans Identification letter of OC curve
AA B E F H J K
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single101312623934134521672978
L M N P Q R S
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
Single4811128418191262627200394031559605009091800140141

nc=Cumulative sample size. Ac=Acceptance number. Re=Rejection number.