Goal Seek¶
Goal Seek finds the input value needed in one cell to make a formula cell reach a target result. It is useful for back-solving scenarios such as "what sales figure is needed to reach a profit of 1000?"
Opening Goal Seek¶
Open it via Data > Goal Seek in the menu bar. The currently selected cell is pre-filled as the "Set cell."
How to Use¶
Fill in three fields:
| Field | Description |
|---|---|
| Set cell | The cell containing a formula whose result you want to control (e.g. B5). Must contain a formula. |
| To value | The target numeric result you want the formula to produce (e.g. 1000). |
| By changing cell | The input cell whose value Goal Seek will adjust (e.g. A1). This cell must be referenced (directly or indirectly) by the formula in the set cell. |
Click Seek to start the solver.
Algorithm¶
Goal Seek uses a Newton-Raphson method with automatic bisection fallback:
- Computes a numerical derivative by evaluating the formula at nearby values.
- Iterates toward the target using Newton steps.
- If Newton steps fail to converge, it falls back to a bisection search by bracketing the root.
- Runs up to 1000 iterations with a tolerance of 1e-7.
Results¶
After solving, the status area shows:
- Whether a solution was found
- The final value of the changing cell
- The resulting value of the formula cell
- The number of iterations used
Accept or Revert¶
- Click OK to keep the solution (the changing cell retains its new value).
- Click Cancel to revert the changing cell to its original value before Goal Seek ran.