Formulation Tools · QC Statistics · USP <905>
Paste assay results as percent label claim to calculate mean, sample standard deviation, %RSD, range, and USP-style content uniformity Acceptance Value.
Blend uniformity evaluates in-process powder mix adequacy using assay RSD across blend samples, while content uniformity (USP <905>) tests individual finished dosage units with Acceptance Value AV = |M − mean| + k×s. For n = 10 use k = 2.4; for n ≥ 30 use k = 2.0, comparing AV to L1 = 15 as an educational stage-one indicator. This calculator supports arithmetic checks only—final compendial release requires the official chapter, product monograph, sampling plan, and quality-unit review.
Core Equations
AV = |M - mean| + k × s
M = mean if 98.5% to 101.5%, otherwise nearest bound · k = 2.4 for n = 10, k = 2.0 for n ≥ 30 · %RSD = sample SD ÷ mean × 100
Enter individual results only. Do not paste batch numbers, sample IDs, or any confidential product information.
Content uniformity
Educational calculation only. Final compendial decisions require the official USP <905> chapter, product monograph, approved specification, sampling plan, and quality-unit review.
Content uniformity AV for n = 10 tablets
Assay results (% label claim): 99.3, 100.4, 98.9, 101.1, 100.2, 99.7, 100.6, 99.9, 100.1, 99.5
Mean = 100.07%, sample SD ≈ 0.68%, k = 2.4, M = mean (within 98.5–101.5%).
AV = |M − mean| + k×s ≈ 0 + 2.4×0.68 ≈ 1.63 — educational pass vs L1 = 15, subject to official USP staged criteria and quality review.
Blend uniformity is an in-process assessment of powder mix adequacy before compression or encapsulation. It is sensitive to sampling location, thief sampling technique, segregation during transfer, API particle properties, and assay method variability.
Content uniformity tests individual finished dosage units and supports dose-to-dose consistency. USP <905> uses staged criteria and an Acceptance Value that penalizes both off-target mean and excessive unit-to-unit variability.
In the common content uniformity calculation, individual dosage unit assay results are expressed as percent label claim. The AV formula combines the sample standard deviation with the distance between the sample mean and a reference value M.
| Input | Educational treatment in this calculator |
|---|---|
| n = 10 | Uses k = 2.4 and compares AV to L1 = 15 as a stage-one educational indicator. |
| n ≥ 30 | Uses k = 2.0 and compares AV to L1 = 15. Official stage-two decisions also depend on individual-unit limits and chapter details. |
| Mean 98.5% to 101.5% | M equals the mean, so the off-target mean term is zero. |
| Mean outside 98.5% to 101.5% | M is set to the nearest bound, adding a penalty for off-target potency. |
ISPE Blend Uniformity and Content Uniformity (BUCU) tools discuss sampling plans and ASTM E2709/E2810 methods intended to estimate confidence that sampled material can meet USP UDU expectations. These approaches are useful for process design, qualification, and continued monitoring, but they are not regulations or substitute acceptance criteria.
Small API mass can amplify sampling error, segregation, and assay variability. Low-dose products often require tighter control strategy justification.
Samples should target locations or time points most likely to reveal highs and lows, such as blender zones, IBC discharge, start-up, middle, and end of compression.
Thief sampling, sample size, depth, powder flow, and blend disturbance can bias results. A low RSD is only meaningful if sampling is representative.
Blend and content uniformity statistics underpin solid oral dose control strategy from development through commercial GMP. Process development uses blend RSD trends to qualify mixing endpoints, while QC applies USP <905> content uniformity to finished units before release. Low-dose and potent products require tighter sampling justification because small assay or sampling errors can fail uniformity even when the process appears visually adequate.
Pair uniformity checks with downstream performance tools: compare dissolution drift using the Dissolution Comparison Calculator, investigate compression weight issues with Tablet Compression Troubleshooting, and quantify process risk with the RPN Calculator when uniformity failures trigger CAPA.
Competitive landscape: Pharmaguddu and similar pharma education sites publish USP <905> explanations and forum examples but rarely offer an interactive AV/RSD calculator with ISPE sampling caveats. NovaPharmaNews combines blend and content modes, educational L1 comparison, and links to dissolution, compression, and QA risk tools in one free workflow.