Need to project a trend beyond your data? This linear extrapolation calculator fits a straight line to your data points and extends it to forecast future values.
Linear Extrapolation Calculator
Using the calculator
Enter at least two data points, then specify your target X value. The calculator fits a line using least squares regression and projects the Y value at your target.
You'll see the slope, R² fit quality, and the equation y = mx + b being used.
What is linear extrapolation?
Linear extrapolation assumes a straight-line relationship continues beyond your known data. The formula:
y = mx + b
Where m is the slope (rate of change) and b is the y-intercept. With multiple points, least squares regression finds the best-fit line.
When to use linear extrapolation
Linear extrapolation works best when:
- Your data shows constant absolute change per period (not percentage change)
- You're projecting a short distance beyond your data
- The underlying process is genuinely linear
For percentage-based growth (like compound interest or population), consider exponential extrapolation instead.
