# Interpolation Calculator

> Estimate a y value between two known points using the linear interpolation formula. Shows the working and flags when the target x falls outside the known range.

**URL:** https://www.calculatoranswers.com/interpolation-calculator
**Category:** Education

## Quick Answer

Estimate a value between two known points. Enter both (x, y) pairs and a target x to get the linearly interpolated y, with the working shown and extrapolation flagged when the target falls outside the pair.

## Definition

An interpolation calculator estimates the value of a function at an unsampled point from known values nearby. This one performs linear interpolation only: it draws a straight line between two coordinate points and reads the value off that line, using the ratio of differences between the points. It does not perform polynomial, Lagrange, Newton or spline interpolation, which curved data needs. Science students, engineers, and financial analysts use it to estimate intermediate values from lookup tables, experiment data, or financial curves.

## How to Use

1. **Enter the two known points** — Input the x and y of each known point. The two x values must differ, because the line between them would otherwise be vertical.
2. **Set the target point** — Type the value of the independent variable for which you want to estimate the dependent variable.
3. **Check the interpolation badge** — The result is labelled Interpolation when the target x sits between the two known points and Extrapolation when it sits outside them, where a straight line is a weaker assumption.
4. **Read the result** — View the estimated y along with the formula and the slope between the two known points.

## Disclaimer

This calculator provides estimates for educational and planning purposes. Always consult a qualified professional for specific advice on financial, medical, legal, or other regulated decisions.

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