Linear Interpolation Calculator

Linear interpolation estimates an unknown value that falls between two known data points by assuming the points lie on a straight line. If you know (x1, y1) and (x2, y2), you can estimate y at any x between them using the line's equation. It is widely used in data analysis, engineering, and science.

The formula is y = y1 + (x - x1) * (y2 - y1) / (x2 - x1). This calculates the y-value at any x by finding the slope (y2 - y1) / (x2 - x1) and applying it from the first point (x1, y1) to the target x.

Extrapolation is estimating a value outside the range of your two known points. If x is less than x1 or greater than x2, you are extrapolating rather than interpolating. Extrapolation is generally less reliable than interpolation because you are estimating beyond the data you have.

Linear interpolation is ideal when you have two close data points and want to estimate values in between. It is used in temperature tables, stock prices, survey data analysis, and computer graphics. It assumes a linear relationship between the points, which is accurate for small intervals.

Interpolation estimates values between known points using simple formulas like the line through two points. Curve fitting finds a single equation that best represents all your data points. Interpolation is quick and local; curve fitting is global and more complex.