Linear Interpolation Calculator

Author: Henrick Yau
- 5 August 2026
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Calculators

Calculate a value at any point along a line between two known points. Linear interpolation is a method of curve fitting using linear polynomials to construct new data points within the range of a discrete set of known data points.

Formula: y = y₁ + (x - x₁) × (y₂ - y₁) / (x₂ - x₁)

Input Values

Display Options

About Linear Interpolation

Linear interpolation is one of the simplest methods of interpolation, involving the construction of new data points within the range of a discrete set of known data points. It assumes a linear relationship between adjacent points and calculates intermediate values along a straight line between them.

Applications of Linear Interpolation
  • Computer Graphics: Generating intermediate frames in animations
  • Mathematics: Approximating functions at points not directly computed
  • Engineering: Estimating values between measured data points
  • Data Analysis: Filling in missing values in datasets
  • Financial Analysis: Estimating values between known market data points
Limitations of Linear Interpolation

While linear interpolation is computationally simple and easy to implement, it has some limitations:

  • Assumes a linear relationship, which may not represent the actual relationship between data points
  • May provide poor approximations for highly curved functions
  • Not suitable for extrapolation (predicting values outside the range of known data points)

For more accurate interpolation of curved functions, consider higher-order methods such as cubic spline interpolation or polynomial interpolation.

Understanding Linear Interpolation

Linear interpolation is a useful technique for estimating values on a straight line between two existing points. By using a simple formula, you can find a value at any point along this line. This is handy in various fields like science, engineering, and data analysis where precise data is often needed.

How the Linear Interpolation Calculator finds unknown y

The Linear Interpolation Calculator helps you calculate an unknown value by taking two known points. You input the coordinates of these points and the x-value where you want to find y. The calculator then applies the linear interpolation formula and provides you with the desired result.

Key features: input fields, decimal places, steps, graph

  • Easy input fields for x₁, y₁, x₂, y₂, and the interpolation point x.
  • Options to choose decimal places for more accurate results.
  • Ability to display the calculation steps for better understanding.
  • Graph visualization of the results to see the linear relationship visually.

Why Use Linear Interpolation?

Linear interpolation is preferred for its simplicity and speed. It is often sufficient when data points are not too far apart and when the relationship between them is approximately linear. This makes it a go-to method for many practical applications where quick estimates are necessary.

Applications of Linear Interpolation

  • Computer Graphics: Creating smooth transitions in animations.
  • Engineering: Finding unknown measurements in experiments.
  • Data Filling: Completing gaps in data sets for analysis.
  • Financial Predictions: Estimating values between known data points in market analysis.

Limitations of Linear Interpolation

While linear interpolation is easy to use, it does have some limits. It assumes that the points are connected by a straight line, which isn’t always true. This method might not work well for data that has a more complex or curved relationship, leading to inaccuracies.

Understanding the Linear Interpolation Formula

The formula for linear interpolation is simple and effective. It can be written as: y = y₁ + (x - x₁) × (y₂ - y₁) / (x₂ - x₁). Here, (x₁, y₁) and (x₂, y₂) are the two known points, while x is the point where you're estimating y. This formula allows you to find the interpolated value quickly.

Getting started: enter points and x to get interpolated value

Using the Linear Interpolation Calculator is easy. Just enter the values for the two known points and the x-value you want to interpolate. With a click of a button, you’ll get the interpolated value along with the slope and the linear equation. This tool is perfect for students, engineers, and anyone who needs quick calculations.

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