Uniformity of Dosage Unit by Weight Variation Method

USP <905> Weight Variation Acceptance Value Calculator

For uncoated or film‑coated tablets, weigh 10 dosage units individually, then calculate each unit’s content as % of label claim using the weight and a common assay result.

Common Parameters

Assay Result (%)

L1 Stage – Tablet Weights (10 Units)

Unit	Weight (mg)	Content (% LC)
1		-
2		-
3		-
4		-
5		-
6		-
7		-
8		-
9		-
10		-

L1 stage must have exactly 10 units.

L2 Stage – Additional Tablet Weights (20 Units)

Unit (Additional)	Weight (mg)	Content (% LC)
1		-
2		-
3		-
4		-
5		-
6		-
7		-
8		-
9		-
10		-
11		-
12		-
13		-
14		-
15		-
16		-
17		-
18		-
19		-
20		-

L2 additional table must have exactly 20 rows. (Overall, L2 stage uses 10 from L1 + these 20 = 30 units.)

Calculation Case

Select Case:

Overall Results

L1 Stage (10 Units)

Total Units:

Mean Content (% LC): %

Standard Deviation (s):

Reference Value (M): %

Acceptance Value (AV):

L2 Stage (30 Units: 10 from L1 + 20 Additional)

Total Units:

Mean Content (% LC): %

Standard Deviation (s):

Reference Value (M): %

Acceptance Value (AV):

Calculation Details:

Individual Content (% LC) = (Individual Weight ÷ Mean Weight) × (Assay Result)

AV = |M – Mean| + k × s
For Case 1 (T ≤ 101.5):
• If 98.5% ≤ Mean ≤ 101.5%, then M = Mean (AV = k × s)
• If Mean < 98.5%, then M = 98.5 (AV = (98.5 – Mean) + k × s)
• If Mean > 101.5%, then M = 101.5 (AV = (Mean – 101.5) + k × s)

For Case 2 (T > 101.5):
• If 98.5% ≤ Mean ≤ T, then M = Mean (AV = k × s)
• If Mean < 98.5%, then M = 98.5 (AV = (98.5 – Mean) + k × s)
• If Mean > T, then M = T (AV = (Mean – T) + k × s)

USP <905> requires AV ≤ 15.0 for L1 and AV ≤ 25.0 for L2.
Note: k = 2.4 for a 10-unit test (L1) and k = 2.0 for a 30-unit test (L2).
Additionally, for L2, each individual content must lie within [1 – (0.01×25)]×M and [1 + (0.01×25)]×M, i.e., between 0.75×M and 1.25×M.