Chemistry

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Calibration Curve Calculator.

Fit a straight-line calibration curve to three explicit standards and predict an unknown.

On-device calculationNo signup
01

Set your values

Results update as you type.

Slope: 2

Slope

2.00
Intercept: 1

Intercept

1.00
Predicted y: 4

Predicted y

4.00

How to Use

A least-squares straight line y = intercept + slope × x is fitted to the three entered standards.

Use a named source convention for coefficients and units. This page does not provide laboratory, medical, species, or food-safety advice.

Use Cases

Quantitative analysis in the lab

Determine the concentration of an unknown sample by fitting a linear calibration curve to three standard solutions and using the unknown's response.

Example: Measure absorbance of standards at 0, 0.5, and 1.0 mg/L, then find concentration of a sample with absorbance 0.45.

Educational tool for chemistry students

Help students understand the concept of calibration curves and linear regression by providing a quick way to calculate unknown concentrations from standard data.

Example: Use in a lab exercise to verify the concentration of a dye solution.

Frequently Asked Questions

How does the calibration curve calculator work?
You input the concentrations and responses for three standard solutions. The calculator performs a linear regression to find the best-fit line (y = mx + b). Then, you can enter the response of an unknown sample, and it calculates the corresponding concentration using the fitted line.
What is a calibration curve used for?
A calibration curve is used in analytical chemistry to determine the concentration of an unknown sample by comparing its response (e.g., absorbance, signal) to a series of known standards. It establishes a relationship between response and concentration.
Can I use more than three standards?
This calculator is specifically designed for three standards. For more standards, you would need a different tool that can handle multiple data points for a more robust regression.

Tips & Common Mistakes

Tips

  • Ensure your standards cover the expected range of the unknown concentration for accurate interpolation.
  • Use at least three standards to check for linearity, but this calculator is limited to exactly three.
  • Double-check that the response values are in the same units and scale for all standards and the unknown.
  • If the unknown's response falls outside the range of your standards, the prediction may be less reliable.

Common Mistakes to Avoid

  • Entering the standards in the wrong order or mixing up concentration and response values.
  • Using a non-linear relationship when the data is not linear, which this calculator cannot handle.
  • Forgetting to include a blank (zero concentration) standard, which can bias the intercept.

Last updated: August 13, 2026