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Instant result
Enter the data and press the button to do the calculation.
Online Calculator
Linear interpolation calculator
Enter two points and an x value to estimate y on the line connecting them.
Information
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Local processing
The values are processed directly in your browser.
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Free
No registration, external API or subscription required.
Frequently asked questions
What's the formula?
y = y₁ + (x - x₁)(y₂ - y₁)/(x₂ - x₁).
What happens if x₁ and x₂ are equal?
The result cannot be calculated because it would involve division by zero.
Can it be used outside the range?
Mathematically, yes, but in that case it would be extrapolation and not interpolation.
Does it also show the slope?
Yes.