%RSD Calculator for HPLC Precision and System Suitability

Paste replicate injections or results and check %RSD against your limit.

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Replicate values (one per line, or separated by commas)

%RSD limit %

Example: six replicate standard injections for system suitability.

n–

Mean–

SD–

%RSD–

95% CI of mean–

SD = √(Σ(x − x̄)²/(n − 1)) · %RSD = SD/x̄·100 · CI = x̄ ± t(0.975, n−1)·SD/√n

How it works

Relative standard deviation is the standard measure of precision in chromatography. For system suitability, USP <621> commonly uses five or six replicate injections of a standard with a limit such as 2.0% for assays; Ph. Eur. 2.2.46 sets the allowed RSD from the specification width and the number of injections.

For method validation, ICH Q2(R2) distinguishes repeatability (same analyst, same day), intermediate precision (different days, analysts or equipment) and reproducibility (between laboratories).