How to Compare Two Excel Files and See What Actually Changed

Someone sends back the model with changes. They did not track them, they did not tell you what moved, and the file name says v4_FINAL_updated. You need to know what actually changed before you sign off on anything.

Excel gives you a few ways to do this. None of them are great, and one specific thing breaks most of them. Here is what works, what does not, and why.

Option 1: Spreadsheet Compare

Microsoft ships a tool called Spreadsheet Compare, which does a real cell-by-cell diff and colour-codes the results by type: entered values, formulas, formatting, and so on. It is the most capable native option.

The catch is availability. It comes with Office Professional Plus and Microsoft 365 Apps for enterprise, not with Home, Personal, or standard Business plans. If you cannot find it in your Start menu, your licence probably does not include it. The related Inquire add-in has the same restriction.

Option 2: View Side by Side

Open both files, then View > View Side by Side, with Synchronous Scrolling turned on. Both windows scroll together so you can read across.

This is fine for a quick look at a small sheet and hopeless on a real model. You are doing the diff with your eyes, across dozens of tabs, and a changed constant buried inside a formula looks identical to one that was not touched.

Option 3: Show formulas, then compare

Press Ctrl + ` `` (the backtick, above Tab) in each file to switch from values to formulas. This is genuinely useful, because it exposes the change that matters most: a formula that quietly became a typed number.

It pairs well with a hardcode scan. If you want the detail on that, we wrote up how to find hardcoded numbers in an Excel model separately.

Option 4: A helper column

If both files have identical layouts, open a third workbook and point a formula at the same cell in each:

=IF([Old.xlsx]Sheet1!A1<>[New.xlsx]Sheet1!A1, "CHANGED", "")

Fill it across the used range and you have a crude change map. It is free, it works on any Excel licence, and it takes about ten minutes to set up per sheet.

The thing that breaks all of this

One inserted row. Insert a row at the top of a schedule and every cell below it shifts down by one. A naive comparison now reports the entire sheet as changed, because A47 in the old file is A48 in the new one. The helper column becomes noise. Spreadsheet Compare handles some of this, but a manual diff does not.

This is why most people give up on comparing versions and just re-check the outputs. It is also why a comparison that does not track inserted and deleted rows is close to useless on a model that someone has actually worked in.

What you actually want to know

Not every change carries the same weight. In a financial model there is a clear hierarchy:

• A changed input. Someone moved an assumption. This changes your answer, and it is the single most consequential edit anyone can make.
• A changed formula. The logic moved. Sometimes a fix, sometimes a break.
• A formula that became a constant. Someone typed over a calculation to force a number. This is the one that survives review and causes trouble later.
• Formatting. Almost never worth your attention during a review.

A diff that dumps all four into one undifferentiated list makes you do the triage yourself, which is most of the work.

How ExcelSurge does it

Compare Workbooks diffs two versions and tracks inserted and deleted rows across sheets, so a single insertion does not report hundreds of shifted rows as changes. Changed inputs are flagged as high risk and summarised separately, because a moved assumption is the edit most likely to change your conclusion.

It runs locally on your machine, like everything else in the add-in, so neither version of the model goes anywhere. There is more on that on the security page.

If you are weighing tools for this, the comparison page shows which of them do workbook diffing at all. It is a smaller list than you would expect.