Quick Navigation
FORECAST.LINEAR Function
Summary
The FORECAST.LINEAR function predicts a future value using simple linear regression analysis. It calculates the best-fit straight line through known data points and extends it to estimate values for new x-values, making it ideal for trend analysis and basic forecasting.
Syntax
FORECAST.LINEAR(x, known_y's, known_x's)Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| x | Number |
Yes | Target x-value for prediction |
| known_y's | Range/Array |
Yes | Dependent variable data points |
| known_x's | Range/Array |
Yes | Independent variable data points |
Using the FORECAST.LINEAR Function
FORECAST.LINEAR fits a straight line to historical data using the least squares method and predicts future values. It's perfect for sales forecasting, trend projection, and any scenario where data shows a consistent linear pattern over time.
Common FORECAST.LINEAR Examples
Basic Sales Forecast
=FORECAST.LINEAR(13, B2:B12, A2:A12)Predicts next month's sales (month 13) based on 12 months of historical sales data.
Temperature Prediction
=FORECAST.LINEAR(75, C2:C20, B2:B20)Estimates temperature at 75 degrees longitude based on existing weather data points.
Budget Projection
=FORECAST.LINEAR(E5, SalesData[Amount], SalesData[Month])Projects budget needs for target month E5 using structured sales table.
Frequently Asked Questions
Common Errors and Solutions
#VALUE! error
Cause: x is not numeric, or known_y's and known_x's arrays have different sizes
Solution: Ensure all inputs are numeric and arrays match in size
#N/A error
Cause: known_x's array doesn't contain the x value
Solution: Verify x falls within or extends known_x's range logically
Inconsistent array sizes
Cause: known_y's and known_x's have different numbers of elements
Solution: Match array dimensions exactly
Notes
- Performs y = mx + b linear regression where m = slope, b = y-intercept
- Assumes perfect linear relationship (R²=1 would be perfect fit)
- x should logically extend beyond known_x's for true forecasting
- Same algorithm as Excel's TREND function for single predictions
Compatibility
Available in: Excel 2016, Excel 2019, Excel 2021, Excel for Microsoft 365
Not available in: Excel 2013 and earlier versions
Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2016+, Excel for Microsoft 365