How to use the linear interpolation calculator
Estimate a value between two known points assuming a straight line between them. Enter known x at point 1, known y at point 1, known x at point 2, known y at point 2, position to estimate in the fields above; the interpolated value is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “linear interpolation”, “estimate between two points”, “interpolate value”, “calculate linear interpolation”, “find interpolated value”.
Formula
Variables
- x1 — Known x at point 1
- y1 — Known y at point 1
- x2 — Known x at point 2
- y2 — Known y at point 2
- x — Position to estimate
Worked example
With known x at point 1 = 2, known y at point 1 = 10, known x at point 2 = 6, known y at point 2 = 30, position to estimate = 4, the calculator gives interpolated value ≈ 20.
Frequently asked questions
What is the linear interpolation calculator used for?
Estimate a value between two known points assuming a straight line between them. It helps with questions such as “linear interpolation”, “estimate between two points”, “interpolate value”.
What is the formula for the linear interpolation calculation?
Interpolated value = y1+(x-x1) × (y2-y1) / (x2-x1). Here x1 is known x at point 1, y1 is known y at point 1, x2 is known x at point 2, y2 is known y at point 2, x is position to estimate.
What inputs do I need for the linear interpolation calculator?
You need known x at point 1, known y at point 1, known x at point 2, known y at point 2, position to estimate. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the linear interpolation calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the linear interpolation result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.