LOD/LOQ Calculator

Calculate the limit of detection (LOD) and limit of quantification (LOQ) per ICH Q2(R2) — enter the response's standard deviation and calibration slope for instant results.

Limit of detection (LOD) and limit of quantification (LOQ) define the lowest concentrations an analytical method can reliably detect and quantify, respectively. LOQ is always the higher of the two, since quantifying a result with acceptable accuracy and precision demands a larger signal margin above background noise than merely detecting the analyte’s presence.

This calculator uses the ICH Q2(R2) standard-deviation-of-response/slope approach: LOD = 3.3(σ/S) and LOQ = 10(σ/S), where σ is the standard deviation of the response (typically from calibration-curve residuals or blank replicates) and S is the calibration curve’s slope. Both results are rounded to three significant figures.

For the full comparison of these two parameters and how each is estimated in practice, see Difference Between Limit of Detection (LOD) and Limit of Quantification (LOQ).

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