Least-squares line, parabola, exponential, geometric, and power curve fitting with full equation tables.
Tip: use samples, upload, copy, download, and send-to actions inside the workspace where available.
Curve Fitting Calculator is a free, browser-based tool that helps you get the job done quickly. Least-squares line, parabola, exponential, geometric, and power curve fitting with full equation tables. It's built for speed and privacy: Everything runs locally in your browser — your data is never uploaded to a server. No sign-up, no installs, and no daily limits.
Use this tool as the focused step in a larger browser-based workflow.
Review the preview, copy or download the result, and keep everything local in your browser.
System of Linear Equations: Solve linear systems with RREF, Gauss-Jacobi, and Gauss-Seidel methods using full step-by-step tables.
Open toolInterpolation Calculator: Step-by-step Newton forward/backward, divided difference & Lagrange interpolation with full tables.
Open tool| i | x | y | Action |
|---|---|---|---|
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 |
| x | 0 | 5 | 10 | 15 | 20 |
|---|---|---|---|---|---|
| y | 7 | 11 | 16 | 20 | 26 |
| x | y | xy | x² |
|---|---|---|---|
| 0 | 7 | 0 | 0 |
| 5 | 11 | 55 | 25 |
| 10 | 16 | 160 | 100 |
| 15 | 20 | 300 | 225 |
| 20 | 26 | 520 | 400 |
| Σx = 50 | Σy = 80 | Σxy = 1035 | Σx² = 750 |
| 750 | 50 | 1035 |
| 50 | 5 | 80 |
| 1 | 0.0667 | 1.38 |
| 50 | 5 | 80 |
| 1 | 0.0667 | 1.38 |
| 0 | 1.6667 | 11 |
| 1 | 0.0667 | 1.38 |
| 0 | 1 | 6.6 |
| 1 | 0 | 0.94 |
| 0 | 1 | 6.6 |
| 1 | 0 | 0.94 |
| 0 | 1 | 6.6 |
| x | observed y | fitted y | residual | residual² |
|---|---|---|---|---|
| 0 | 7 | 6.6 | 0.4 | 0.16 |
| 5 | 11 | 11.3 | -0.3 | 0.09 |
| 10 | 16 | 16 | 0 | 0 |
| 15 | 20 | 20.7 | -0.7 | 0.49 |
| 20 | 26 | 25.4 | 0.6 | 0.36 |
| Σ residual² | 1.1 | |||
Residual is observed y - fitted y. Smaller SSE/RMSE means a closer least-squares fit for the selected model.
