Microsoft Excel · Analysis and charts · Intermediate
Find the required input with Goal Seek in Excel
Find the required input with Goal Seek in Excel with a complete practice example, expected results and recovery checks.
Official documentation reviewed; example logic independently checked; native Excel execution not performed · Editorial standards
Quick answer: Use Data → What-If Analysis → Goal Seek with a formula result as Set cell, the desired result as To value, and one numeric input as By changing cell. The formula must depend on that input; Goal Seek does not solve an unrelated cell.
Version and platform: Microsoft 365 Excel for Windows desktop; Mac, Excel for the web and Excel 2013 interfaces not covered. Use a disposable workbook for the exercise.
Build a model with an independently checkable answer
In a blank worksheet, enter these labels in A1:A5 and values/formula in B1:B5:
| Label | Value or formula |
|---|---|
| Units | 10 |
| Price per unit | 25 |
| Cost per unit | 10 |
| Fixed cost | 300 |
| Surplus | =B1*(B2-B3)-B4 |
At 10 units, the model returns -150: each unit contributes 15, and 150 does not cover the fixed cost of 300. The task is to find the units needed for a surplus of 600, keeping price and costs fixed. This is a synthetic arithmetic model, not an actual sales forecast or purchase decision.
Save the starting workbook. Do not type the target 600 over B5; that would replace the formula Goal Seek needs. Keep B1 as a plain numeric input and confirm that changing it affects B5 before using the tool.
Run Goal Seek
- Choose Data → What-If Analysis → Goal Seek in Excel for Microsoft 365 on Windows.
- Set Set cell to
$B$5, the formula result. - Set To value to
600. - Set By changing cell to
$B$1, the units input. - Select OK and inspect the reported result and the resulting worksheet values. Keep the result only after it makes sense for the model.
The expected input is approximately 60 units, with B5 approximately 600. Verify independently: 60 × (25 − 10) − 300 = 600. Numerical solving can produce a result close to the target rather than an exact decimal representation, so inspect sufficient decimal places and the formula result rather than trusting a rounded display alone.
Test a changed assumption
Change B4, the fixed cost, from 300 to 450. With 60 units still in B1, B5 becomes 450. Re-run Goal Seek using the same target 600 and changing cell B1. The required input should become approximately 70, because 70 × 15 − 450 = 600.
This is not an automatic live solution: changing fixed cost does not continuously rerun Goal Seek. It changes the normal formula result until you explicitly solve again. Save this final practice workbook as XLSX, reopen it, and verify B1 is about 70 and B5 about 600. The worksheet retains values and formulas; do not describe the saved file as a continuously running optimization.
Diagnose failures and unrealistic answers
If Set cell is a typed number, restore the formula. If the changing cell is not a dependency, correct the model connection rather than repeatedly pressing OK. If the solver cannot find a result, consider whether the target is reachable at all. For example, with price equal to unit cost, changing Units cannot offset the fixed cost in this model.
Goal Seek changes one variable and does not impose a whole-number, nonnegative or capacity constraint. If another target produces a fractional number of units, decide what that means before using it operationally; rounding the input changes the output. Use a more appropriate constrained method for multiple variables or hard bounds. Do not interpret a numerical solution as evidence that demand, capacity or the assumptions are realistic. Restore the original saved copy if you want to discard the practice changes.
Official references
Documentation snapshots retrieved 20 October 2026. These instructions and example checks are documentation-based; no native Excel run or application screenshot is claimed.