You have three realistic options for seeing what changed between two Excel files: put them side by side in Excel and scan by eye, flag unequal cells with a comparison formula, or run both files through a comparison tool. The first two are honest but only show you where cells differ. Only the third gives you a reviewable list of changes.
Comparing two files usually means two versions of the same workbook. The budget as Budget-v3.xlsx and as Budget-v7.xlsx, or the model before and after a colleague’s edits. The question that matters is what exactly moved, and whether any of it was wrong. This guide is organized around that job.
Which method fits the job?
| You need | Use |
|---|---|
| A quick look at a region you already suspect changed | View Side by Side |
| Every cell that no longer matches, flagged in place | A comparison formula, with conditional formatting if you want color |
| A reviewable list of every change, including inserted rows and formula edits | A comparison tool |
The first two are built into desktop Excel and cost nothing but time. Their shared weakness is that they compare by position, cell address against cell address, so they hold up only while the two files still have the same shape. The third category is what Microsoft’s Spreadsheet Compare does on qualifying Office editions, and what a free in-browser comparison does everywhere else.
How do I view two Excel files side by side?
Open both workbooks. On the View tab, in the Window group, click View Side by Side. If you have more than two workbooks open, Excel shows a Compare Side by Side dialog and asks which one to pair with the active file. Then click Synchronous Scrolling in the same group, so both panes move together as you scroll.
That is the whole feature, and for what it is, it’s useful: a fast way to sanity-check a region you already suspect, with no setup. The limits are just as plain. Nothing gets highlighted, so you’re relying on your eyes to catch a one-digit change in a grid of numbers. And the panes are only aligned by scroll position, so one inserted row on either side quietly shifts everything you’re looking at.
How do I flag changed cells with a formula?
A formula can do the looking for you. Excel’s <> operator tests whether two values are unequal and returns TRUE or FALSE. With both workbooks open, a cell in one file can reference the other file directly: the reference names the workbook in square brackets, then the sheet, then the cell.
Enter that on a blank sheet in the older file (with your own file and sheet names), fill it across the used range, and every TRUE marks a cell that changed between versions.
If juggling cross-file references feels fragile, the pragmatic variant is to copy the sheet from one file into the other workbook and compare two local sheets the same way. And if you want the changed cells shaded in place rather than a grid of TRUEs, the same test works as a conditional-formatting rule; the full walkthrough is on compare Excel sheets and highlight the differences, so it isn’t repeated here.
Know what this method can and cannot tell you. It compares by position, so an inserted row offsets every row below it and each of them reads as changed. It compares values, so two cells showing the same number compare as equal even when the formula behind one of them was rewritten. And TRUE only tells you that a cell differs. To see what the cell was and what it became, you still open both files and look.
What about Microsoft Spreadsheet Compare?
Microsoft ships a dedicated comparison program, Spreadsheet Compare, that compares two workbooks cell by cell, highlights each difference by type, and can check VBA code for changes. Inside Excel, the companion Inquire tab starts the same comparison via Compare Files.
The catch is getting it. Microsoft’s support page states the limit outright: “Spreadsheet Compare is available only in Excel for Windows in Microsoft 365 Apps for enterprise plans and equivalent editions.” On a Mac or in the browser it is not there at all, it is commonly missing from Home and Business plans, and there is no standalone download. Which editions carry it, and what to use when yours doesn’t, is covered in the Spreadsheet Compare alternative guide.
How do I get the full change list in the browser?
The remaining option works on any system and takes one drag. Load the old file and the new one into the free comparison and it shows every changed cell, formula, sheet, and structural edit, right in your browser, with nothing sent to a server. The result reads green for added, red for removed, amber for changed, sheet by sheet, and every changed cell shows the old value next to the new one.
The structural part matters more than it sounds. Because the comparison aligns the two files before comparing, an inserted or deleted row shows up as one change instead of shifting everything below it into false positives. That is exactly the case where the side by side view and the positional formula both fall over.
Comparing two sheets inside one workbook?
A related but distinct job: the “before” and “after” are two tabs in the same file, or two lists you need to reconcile by key rather than by position. The methods overlap, but the setup and the failure modes differ enough that it has its own guide. How to compare two Excel sheets walks through every in-Excel method for that case, including Power Query merges and lookup checks, with a note on where each one breaks.
The short version
Side by side viewing is a spot-check, the comparison formula is a positional flag, and both stop short of telling you what actually changed. When the files are two versions of a workbook that matters, get the change list: Spreadsheet Compare if your Office edition includes it, or the free in-browser comparison on anything. And if the deeper question is who changed what over time, not just between two saved copies, that is a version-history problem; tracking changes in Excel covers it.
