In Excel: use Excel desktop on Windows or Mac: open Data ▸ What-If Analysis ▸ Goal Seek, set "Set cell" to the formula whose result you want to hit, type the target in "To value", and pick the single input cell Excel should adjust in "By changing cell". In Excel for the web, Goal Seek is not available; you can view saved results but must run Goal Seek in Excel desktop.
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Open the workbook in Excel desktop on Windows or Mac; Goal Seek cannot run in Excel for the web.
Build the target formula in one cell (e.g. B10, the PMT payment) so it depends, directly or indirectly, on a single adjustable input cell (e.g. B2, the rate).
Open Data ▸ What-If Analysis ▸ Goal Seek.
Set "Set cell" to the formula cell (B10).
Enter the exact number you want in "To value" (900).
Set "By changing cell" to the input Excel should adjust (B2).
Click OK; Excel reports the found value in a confirmation dialog — click OK again to keep it, or Cancel to revert.
What this does
Goal Seek is single-variable what-if analysis: it repeatedly recalculates one formula cell while nudging one input cell, iterating until the formula lands on (or very close to) the target value you specify. It works backwards from a known desired outcome to the unknown input that produces it, which is the opposite of normal spreadsheet work where you plug in inputs and read off a result. It changes exactly one input cell — for several unknowns at once, or for constraints like "keep this cell under 10", use Solver instead, which Goal Seek is not a substitute for. Before you run it on a workbook other people depend on, try it on a copy or a few rows first. Undo only reaches back through the current session, so a quick trial run is the cheapest way to see exactly what will change before the file is saved and shared. The difference between a quick fix and a sheet you can trust is the extra minute you spend validating “where to find goal seek in excel”. Start on a copy or a tiny sample, keep the affected cells visible, and compare the result with the outcome you expected before you touch the real workbook. When this is a ribbon command, the selection matters more than the button: confirm the range, apply the command, then spot-check the output before saving. The point is a calculation you can defend to a CFO or an auditor, but the practical win is that someone else can open the file and understand what happened without asking you.
A worked example
A $200,000, 30-year loan sits in B1 (principal), B2 (annual rate, guessed at 6%) and B3 (term in years), with the monthly payment in B10 as =PMT(B2/12,B3*12,-B1), which currently returns $1,199.10. To find the rate that brings the payment down to exactly $900/month: open Goal Seek, set "Set cell" to B10, "To value" to 900, and "By changing cell" to B2. Excel iterates and rewrites B2 to 3.517%, at which point B10 recalculates to exactly $900.00. Reach for Goal Seek whenever you know the outcome you want — a target loan payment, a break-even price, a required exam average — but not the input that produces it. Instead of guessing values by hand and recalculating, let Excel iterate to the answer in seconds. If this is something you do often, add the command to the Quick Access Toolbar (right-click it on the ribbon and choose Add to Quick Access Toolbar) or learn its shortcut, so next time it is one click instead of a hunt through the menus.
In Google Sheets
This is a command rather than a formula, so there is no syntax to carry over. Google Sheets arranges its commands in menus across the top instead of a ribbon, names some of them differently and does not have every Excel command — look for the equivalent in the Sheets menus or its help before assuming the steps match. The aim was to get you unstuck fast and leave you a little more capable than a copy-paste would. The answer is at the top and the detail above shows why it holds — so the next time a colleague asks, you can answer without reaching for search. Treat “where to find goal seek in excel” as a routine rather than a one-off. Once you know which setting or command controls it, the same few steps handle every workbook where it comes up in Excel, and you can explain them to a colleague in a sentence.
Common mistakes
- Pointing "Set cell" at a cell that has no formula dependency on "By changing cell" — Goal Seek has nothing to iterate and returns an error or no movement.
- Choosing a "By changing cell" that itself holds a formula rather than a raw input — Goal Seek needs a hard, editable value to adjust.
- Expecting Goal Seek to solve for more than one unknown at once — it changes exactly one cell; multiple simultaneous unknowns need Solver.
- Setting an unreachable target (e.g. a payment lower than the principal-only floor), which leaves Goal Seek stuck at its iteration limit without a real solution.
- Clicking Cancel on the results dialog and then being confused why the input cell looks unchanged — Cancel deliberately reverts it to the original value.
Frequently asked questions
Can I use Goal Seek in Excel for the web?
In Excel for the web, Goal Seek is not available; you can view saved results but must run Goal Seek in Excel desktop.
What is the difference between Goal Seek and Solver?
Goal Seek adjusts exactly one input cell to hit one target value. Solver adjusts multiple cells at once and can add constraints while maximizing or minimizing an objective — reach for Solver once you have more than one unknown.
Why does Goal Seek say it cannot find a solution?
Usually because "Set cell" is not actually calculated from "By changing cell" through a formula chain, or because the target value is mathematically unreachable given the formula.
Does Goal Seek permanently change my input cell?
Yes — once you accept the result, it overwrites "By changing cell" with the solved value. Keep a copy of your original assumptions in another cell first if you need to compare before/after.