Fit Results
Enter at least two data points to see the fitted curve.
Why use a curve fitting calculator?
Curve fitting (also called regression) is the process of finding a mathematical function that closely matches a set of observed data points. It is used everywhere from science labs estimating reaction rates, to analysts modelling growth, to engineers calibrating sensors. This calculator supports the models people reach for most often: a straight line for proportional trends, polynomials for gentle curves, exponential and power laws for growth and decay, logarithmic curves for diminishing returns, the logistic S-curve for saturating growth, and the Gaussian bell curve for peaks and distributions.
For linear, polynomial, and logarithmic models the fit is solved exactly using least squares, so the result is deterministic and instant. For the nonlinear models the tool runs a Levenberg-Marquardt optimizer with a sensible starting guess, the same battle-tested algorithm used by scientific software. The reported R-squared value ranges from 0 to 1 — the closer to 1, the better the curve explains the variation in your data — while RMSE reports the typical error in the original units.
Need related math tools? Try the Scientific Calculator for one-off evaluations, the Percentage Calculator for quick ratios, or the 3D Function Plotter to visualize multivariable functions. You can export your fitted coefficients as JSON or download per-point predictions and residuals as CSV for further analysis.