Calibration Curve Calculator
Enter your standard concentrations and responses to generate a calibration curve. Then enter an unknown sample response to find its concentration using linear regression.
Concentration of first standard (use 0 for blank)
Instrument response for standard 1
Concentration of second standard
Instrument response for standard 2
Instrument response of your unknown sample
What is a calibration curve?
A calibration curve (standard curve) is a graph showing the relationship between instrument response (y-axis, e.g., absorbance) and known concentrations (x-axis). It is used to determine the concentration of unknown samples by measuring their response and finding the corresponding concentration from the curve.
How do you create a calibration curve?
1) Prepare standards with known concentrations, 2) Measure instrument response for each, 3) Plot concentration (x) vs. response (y), 4) Fit a line (y = mx + b) using linear regression, 5) Use the equation to calculate unknown concentrations from their responses.
What is the difference between calibration curve and standard addition?
Calibration curve uses external standards in pure solvent, assuming the matrix doesn't affect response. Standard addition spiked known amounts into the actual sample to account for matrix effects. Use standard addition when sample matrix interferes with the measurement.
What is R² (coefficient of determination)?
R² measures how well the regression line fits the data. R² = 1 means perfect fit (all points on the line). R² > 0.99 is excellent, > 0.95 is good for most analytical work. Lower R² indicates poor linearity or experimental error.