🔀 Chromatographic Resolution Calculator
Calculate resolution (Rs) between two adjacent chromatographic peaks from their retention times and baseline widths.
Frequently asked questions
What resolution value counts as 'baseline separated'?
Rs = 1.5 is the conventional threshold for baseline resolution between two peaks of similar size, meaning the peaks return to baseline between them. Many regulatory methods require Rs ≥ 1.5-2.0 for critical peak pairs as a system suitability criterion.
Should I use baseline width or half-height width?
This calculator uses baseline peak width (tangent method), the classical resolution formula. USP also permits an equivalent half-height width formula (Rs = 1.18×(t2-t1)/(W0.5,1+W0.5,2)) which is easier to measure from modern integrator output — both give comparable results for Gaussian peaks.
Does peak order matter?
Yes — enter t1 and t2 in elution order (t1 is the earlier-eluting peak, t2 is the later one). Entering them out of order will give a negative or incorrect resolution value.
Accuracy & how this is derived
Derivation: Standard USP baseline-width resolution formula: Rs = 2(t2-t1)/(W1+W2), derived from the geometry of two Gaussian peaks and their tangent-drawn base widths.
Validated against: USP General Chapter <621> Chromatography, system suitability resolution requirement.
⚠️ For educational and research support only — verify critical results independently before use in regulated, clinical, or publication-bound work.
✔ Last updated: July 2026 · Report an error
Resolution as a chromatographic system suitability metric
Resolution quantifies how well two adjacent peaks are separated by comparing the distance between their retention times to the average of their base widths. It is one of the most commonly cited system suitability parameters in regulated chromatographic methods, since inadequate resolution between critical peak pairs — such as an analyte and a closely related impurity — can compromise the accuracy of quantification even when each individual peak looks well-formed.