In this article
FORECAST predicts a value on a straight-line trend. It is a compatibility function: Excel keeps it so workbooks from Excel 2007 and earlier still calculate, but Microsoft recommends FORECAST.LINEAR for new work. Both give the same result.
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Syntax
=FORECAST(x, known_y's, known_x's)| Argument | What it means |
|---|---|
x |
New x |
known_y's |
History |
known_x's |
Periods |
Examples
Example 1
=ROUND(FORECAST(A2,{100,108,115,124,130,139},{1,2,3,4,5,6}),1)Result: 146.3. See the worked example table below for more cases.
💡 For new workbooks use FORECAST.LINEAR: it gives the same answer and is the name Microsoft keeps documenting.
FORECAST in practice
Where you will use it
- Opening and checking older workbooks that use FORECAST
- Understanding formulas shared by colleagues on older Excel versions
- Knowing when to swap in FORECAST.LINEAR for clarity
Worked example
| Month | Formula | Result |
|---|---|---|
| 7 | =ROUND(FORECAST(A2,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 146.3 |
| 8 | =ROUND(FORECAST(A3,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 154 |
| 12 | =ROUND(FORECAST(A4,{100,108,115,124,130,139},{1,2,3,4,5,6}),1) | 184.9 |
Results calculated in Excel. Same result as FORECAST.LINEAR.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Using FORECAST in new files | Prefer FORECAST.LINEAR: same result, clearer name, and the function Microsoft keeps improving |
| Mixing old and new names in one model | Pick one style per workbook so formulas are easy to audit |
Related functions
📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.
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