Logarithmic Interpolation Calculator
Calculate linear, log-x, log-y, and log-log interpolation between two known points. Solve forward for Y or reverse the calculation to solve for X.
Solve for
Use when both X and Y are plotted on logarithmic axes.
Which interpolation mode should I use?
| Mode | Use when |
|---|---|
| Linear | Both X and Y are represented on linear scales. |
| Log-X | X is logarithmic and Y is linear. |
| Log-Y | X is linear and Y is logarithmic. |
| Log-Log | Both X and Y are represented on logarithmic scales. |
Worked engineering example
Suppose a PSD curve contains the points 1500 Hz, 2.44 g²/Hz and 2000 Hz, 1.00 g²/Hz. To estimate the PSD at 1731.5 Hz on a log-log segment, enter those two points, enter your target value, choose Log-Log, and solve for Y.
Does the logarithm base matter?
No, as long as the same logarithm base is used consistently throughout the calculation. This calculator uses base-10 logarithms because they are familiar in engineering work and map directly to Excel's LOG10() function.