What is chromatographic resolution (Rs)?

Resolution (Rs) is a dimensionless number describing how well two adjacent peaks are separated. Rs = 1.0 means ~2% overlap; Rs ≥ 1.5 is considered baseline separation with <0.1% overlap.

What is the formula for resolution?

Rs = 2(tₑ₂ − tₑ₁) / (w₁ + w₂) for baseline widths. For half-height widths, substitute w½ values and apply a factor: Rs = 1.18(tₑ₂ − tₑ₁) / (w½₁ + w½₂).

What is a good resolution value?

Rs < 1.0: peaks overlap significantly. Rs = 1.0: ≤2% overlap (usable for quantitation with corrections). Rs ≥ 1.5: baseline resolution, ideal for most analytical work. Rs ≥ 2.0: excellent separation.

What is the difference between baseline width and half-height width?

Baseline width (w) is measured at the base of the peak by tangent lines and equals ≈4σ. Half-height width (w½) is the width at 50% peak height and equals ≈2.355σ. Both are valid; the formula uses a factor of 2 for baseline and 1.18 for half-height.

Which peak should be entered as peak 1 vs peak 2?

Peak 1 should be the peak that elutes first (smaller retention time). Peak 2 is the later-eluting peak. The calculator will flag them if entered in the wrong order.

Resolution Chromatography Calculator

Name: Resolution Chromatography Calculator
Availability: InStock
Author: Nham Vu

Enter retention times and peak widths for two analyte peaks to calculate chromatographic resolution (Rs).

Peak Parameters

Peak Width Measurement Method

Baseline width (w) Half-height width (w½)

Peak 1 (first-eluting)

Retention Time t_R1

min

Width w₁

min

Peak 2 (second-eluting)

Retention Time t_R2

min

Width w₂

min

Resolution Rs

—

Resolution Quality Guide

Rs < 1.0 Overlapping peaks

Rs = 1.0 ~2% overlap

Rs = 1.5 Baseline resolution

Rs ≥ 2.0 Excellent separation

Summary