Math & Statistics Calculator
Linear Interpolation Calculator
Estimate a value between two known points, calculate slope and intercept, solve the inverse x from y, and see whether the result is interpolation or extrapolation.
Known points
Interpolation results
This is a straight-line estimate, not a statistical confidence interval.
See the line and your result
The solid segment joins the known points. A dashed extension marks extrapolation.
Calculation, step by step
Calculate several x values
Enter one x per line, or separate values with semicolons. A decimal comma is allowed. Up to 100 values.
Enter x values to build a comparison table.
| X | Estimated y | Range | Position |
|---|
CSV exports use a dot as the decimal separator.
Interpolation formula
The calculator uses y = y1 + (x - x1) x (y2 - y1) / (x2 - x1). This is the straight-line estimate between the two known points.
It also reports the slope and y-intercept so the line equation can be reused.
Practical uses
- Estimate values from tables, charts or lab readings.
- Fill missing values between two measurements.
- Convert calibration points into a simple linear equation.
Linear Interpolation Calculator FAQ
What is linear interpolation?
Linear interpolation estimates a value between two known points by assuming the change between them is a straight line.
What is extrapolation?
Extrapolation means the target value is outside the known x range. The calculator still computes it, but uncertainty is higher.
Can this calculator solve for x from y?
Yes. Enter a target y value and it calculates the corresponding x when the line is not flat.
What formula does it use?
It uses y = y1 + (x – x1) x (y2 – y1) / (x2 – x1).
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