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Linear Interpolation Calculator

Interpolate Between Data Points

First Data Point

X₁ Value

Y₁ Value

Second Data Point

X₂ Value

Y₂ Value

Interpolation Point

X Value (to find Y)

Enter the X value for which you want to find the corresponding Y value.

📚 Learn the Theory

Complete guide to mathematical interpolation methods, engineering tables, and accuracy considerations.

Read Engineering Guide →

Formula

Y = Y₁ + (X - X₁) × (Y₂ - Y₁) / (X₂ - X₁)

Y = Interpolated value

(X₁, Y₁) = First data point

(X₂, Y₂) = Second data point

X = Value to interpolate at

Common Applications

Property Tables
Steam tables, gas properties, compressibility factors
Equipment Curves
Compressor maps, pump curves, valve coefficients
Material Properties
Temperature-dependent properties, thermal expansion

Important Notes

Linear interpolation assumes a straight line between data points
Extrapolation (X outside X₁-X₂ range) increases uncertainty
For nonlinear data, consider using more sophisticated methods
Ensure X₁ ≠ X₂ to avoid division by zero
Best accuracy when X is close to the midpoint between X₁ and X₂