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In this article
FORECAST.LINEAR predicts a y-value for a given x using a straight-line trend fitted to past data.
Syntax
=FORECAST.LINEAR(x, known_ys, known_xs)| Argument | What it means |
|---|---|
x |
The point to predict (e.g. next month number). |
Examples
Example 1
=FORECAST.LINEAR(13, C2:C13, A2:A13)Month 13 sales from months 1–12.
Common errors and fixes
| You see | Why, and the fix |
|---|---|
Forecast looks silly |
Data has seasonality; a straight line ignores it. Try FORECAST.ETS or the Forecast Sheet (Data tab). |
FORECAST.LINEAR in practice
Where you will use it
- Straight-line sales projection
- Estimate cost at a new volume
- Simple trend lines
Worked example
| Month no. | Formula | Result |
|---|---|---|
| 7 | =ROUND(FORECAST.LINEAR(A2,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 146.3 |
| 8 | =ROUND(FORECAST.LINEAR(A3,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 154 |
| 12 | =ROUND(FORECAST.LINEAR(A4,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 184.9 |
Results calculated in Excel.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Seasonal data | Use FORECAST.ETS |
| Argument order | known_y's before known_x's |
Related functions
TREND · LINEST · FORECAST.ETS
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📎 Practice files for this article
- 📗Practice workbook: Statistics basics22 tasks on realistic sales data — type your formula, the Check column turns green when it is right. Answers sheet included.⬇ XLSX · 34 KB
Free to use for learning. Files with macros (.bas) are plain text — import them with Alt+F11 → File → Import File, and always test on a copy.
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