How to Use Goal Seek in Excel

To use Goal Seek in Excel, go to Data, What-If Analysis, Goal Seek, then set the cell you want to control (Set cell), the target number (To value), and the input Excel should change (By changing cell). Excel works backward and adjusts the input until the output hits your target. It is the fastest way to answer questions like what price gives a 20% margin or what units break even.

What Goal Seek solves

Goal Seek answers reverse questions. Normally a model flows forward: you set inputs and read an output. Goal Seek flips that. You name the output you want, and Excel finds the single input that produces it.

It only ever changes one input cell, and that cell must be a hardcoded value, not a formula. The target cell, by contrast, must be a formula that ultimately depends on the input you are changing. If there is no formula link between them, Goal Seek cannot solve.

Common uses in finance: solving for the revenue that hits a target profit, the discount rate that makes NPV equal zero (a manual IRR), the price that delivers a desired gross margin, or the units that reach break-even.

Run Goal Seek: a break-even example

Say B1 holds units sold (currently 1,000), B2 is price per unit ($50), B3 is variable cost per unit ($30), B4 is fixed costs ($25,000), and B5 calculates profit as =B1*(B2-B3)-B4. Right now profit is negative. You want the units that make profit exactly zero.

1. Click the Data tab, then What-If Analysis, then Goal Seek.
2. In Set cell, enter B5 (the profit formula you want to control).
3. In To value, type 0 (your break-even target). Always type a number here, never a cell reference.
4. In By changing cell, enter B1 (units sold, the input Excel may adjust).
5. Click OK. Excel iterates and lands on 1,250 units, the point where profit is zero.
6. Read the result, then click OK to keep the new input or Cancel to restore the original 1,000.

Read the result and decide whether to keep it

When Goal Seek finishes it shows a dialog reporting whether it found a solution and what the current value is. Critically, it has already written the solved value into your input cell. Clicking OK keeps that change; clicking Cancel reverts it.

Because Goal Seek overwrites your input in place, copy the original value somewhere first if you might want it back, or plan to Cancel after noting the answer. For repeatable analysis, record the solved input next to your model rather than leaving the model in its solved state.

• Set cell: must contain a formula (the output you target).
• To value: a typed number, the result you want.
• By changing cell: must be a single hardcoded input that the Set cell depends on.
• Goal Seek finds one solution near the starting value, so for equations with multiple answers, the starting input matters.

Fix common Goal Seek failures

Goal Seek reports when it cannot find a solution. The fixes are usually simple.

• Cell must contain a value: the By changing cell holds a formula. Goal Seek can only adjust a typed number, so replace the formula with a value or point at the true input.
• Goal Seek may not have found a solution: no input value produces your target (for example, you asked for a margin the cost structure cannot reach), or the starting point is too far off. Try a closer starting value.
• Result is slightly off (like 0.0003 instead of 0): Goal Seek stops within a tolerance. Tighten it via File, Options, Formulas by raising Maximum Iterations and lowering Maximum Change.
• No link between cells: the Set cell does not actually depend on the By changing cell, so changing the input never moves the output. Trace the formula chain and fix the link.