How to use this calculator
Enter x,y rows, choose a model, and supply an x to estimate.
Formula and method
Polynomial models use OLS on centered/scaled x. Exponential and power models fit log(y) linearly. Interpolation uses the adjacent straight segment.
Worked example
For y=x²+1 at x=0,1,2,3,4, quadratic estimate at 2.5 is 7.25.
Assumptions and supported scope
2–500 rows for interpolation; polynomial needs degree+2 rows; exponential/power need ≥3 rows and positive response. Power needs positive x. Interpolation within range only. Transform fits minimize log-scale error.
Method references
Method and worked example checked against the calculator implementation. About our methods · Report a correction