Maths & numbers
Linear interpolation calculator
Estimate a y value on the line through two known points.
A clear answer. Here’s how.
y = y₁+(x−x₁)(y₂−y₁)/(x₂−x₁). The known x values must differ. Reports whether x lies between them (interpolation) or outside them (extrapolation). It assumes a straight-line relationship.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- First x
- 0
- First y
- 10
- Second x
- 10
- Second y
- 30
- Requested x
- 4
Example result
- Estimated y
- 18
- Calculation
- Interpolation