The fastest way depends on what changed and how much data you have

If you have two versions of the same spreadsheet and need to spot the differences, Excel gives you several tools depending on the size of the change. For small files with a few columns, opening both in separate windows and scrolling through them works fine. For larger files or when you need to find every single difference automatically, Excel's built-in comparison features and conditional formatting do the work for you. The method you pick depends on whether you're looking for a few obvious changes or need to catch everything.

The right choice also depends on your Excel version and operating system. Windows users with Excel 2013 or later have access to the Inquire add-in, which automates the entire process. Mac users and those with older versions need to use manual methods or external tools. If your files are extremely large — thousands of rows — exporting to a plain text format and using a dedicated comparison tool is often faster than any Excel method.

Key Takeaways

  • Open both spreadsheets in separate Excel windows by holding Shift and clicking the Excel icon twice, then use View > Arrange All to see them side by side.
  • Use conditional formatting with a formula to highlight cells that differ between two sheets, which catches changes you might miss by eye.
  • The Inquire add-in (available in Excel 2013 and later on Windows) automatically compares two files and shows differences in a new workbook.
  • For very large files, export both to CSV format and use a free text comparison tool like WinMerge or Diffchecker to spot changes faster.

Opening two spreadsheets side by side in Excel

The simplest method for small files is to view both spreadsheets at once. Open the first file in Excel, then hold Shift and click the Excel icon in your taskbar (Windows) or dock (Mac) to open a second Excel window. Open your second file in that window. Now go to the View tab in either window and click Arrange All, then choose Side by Side. Excel will split your screen so you can see both files at once.

This method works best when the files are similar in size and you're looking for obvious changes — a number that shifted, a row that was deleted, a name that was corrected. Scroll through both files at the same pace using the Synchronous Scrolling button (also in the View tab) to keep the rows aligned. If the files are very wide or have many rows, you'll spend a lot of time scrolling and may miss small changes. For files with more than a few hundred rows, this approach becomes tedious and error-prone.

Using conditional formatting to highlight differences

For a more thorough comparison, use conditional formatting to automatically highlight cells that don't match. This works when both files have the same structure — the same columns in the same order, with data in the same rows. First, open both files and decide which one you'll mark up. In the file you want to highlight, select all the data in the first sheet (click the top-left corner where the row and column headers meet to select everything).

Go to Home > Conditional Formatting > New Rule. Choose "Use a formula to determine which cells to format." In the formula box, type a formula that compares the current cell to the matching cell in the other file. For example, if your other file is called "Original.xlsx" and you're comparing Sheet1, the formula would be: =Sheet1!A1<>[Original.xlsx]Sheet1!A1. The <> symbol means "not equal to." Click Format, choose a fill color (bright yellow or red works well), and click OK. Every cell that differs from the matching cell in the other file will now be highlighted.

This method catches every difference, including changes to formulas, formatting, and hidden rows. The downside is that both files must be open at the same time, and if the structure changed — if rows were inserted or columns moved — the comparison will be off. Once you close the second file, the highlighting will show errors instead of results, so save your findings before closing anything.

Using the Inquire add-in for automatic comparison

If you're using Excel 2013 or later on Windows, the Inquire add-in can compare two entire workbooks and show you a detailed report. First, make sure Inquire is turned on: go to File > Options > Trust Center > Trust Center Settings > Trusted Add-ins, and look for Inquire in the list. If it's not there, go to File > Options > Add-ins, select COM Add-ins from the Manage dropdown, and click Go. Check the box next to Inquire and click OK.

Once Inquire is active, open one of the files you want to compare. Go to the Inquire tab and click Compare Files. Select the first file, then the second file, and click Compare. Excel will create a new workbook showing every difference — cells that changed, rows that were added or deleted, formulas that were modified, and even formatting changes. Each difference is clickable, so you can jump to the exact location in either file. This is the most thorough method and requires the least manual work, and the results stay in a separate file you can review or share later.

Comparing very large files with external tools

If your spreadsheets are thousands of rows long or the Inquire add-in isn't available on your system, exporting to CSV and using a dedicated comparison tool is faster. Save both Excel files as CSV (Comma Separated Values) by going to File > Save As, choosing CSV format, and clicking Save. You'll get a warning that some formatting will be lost — that's fine for comparison purposes.

read a free text comparison tool like WinMerge (Windows), Diffchecker (web-based, works on any computer), or Meld (Mac and Linux). Open both CSV files in the tool, and it will show you every line that differs, with the changes highlighted. These tools are designed for comparing text files, so they're much faster than Excel for large datasets. The trade-off is that you lose Excel's ability to understand formulas — you're comparing the raw data and formulas as text, not their calculated values. For most comparison work, this doesn't matter, since you're looking for what changed, not what it means.

Handling spreadsheets with different structures

If the two files have different numbers of columns, different column order, or rows in a different sequence, none of the methods above will work well. In this case, you need to standardize the structure first. Open both files and manually rearrange one so the columns match the other. If rows are in a different order, sort both files by the same column (usually an ID number or name) so they line up.

Once the structure matches, use the conditional formatting method or Inquire to find the differences. If the files are very different — different columns entirely, different row counts, different purposes — you may not actually need a comparison tool. Instead, think about what you're trying to learn: Are you checking whether data was entered correctly? Are you tracking what changed between versions? Are you merging two files? The answer to that question will tell you whether a comparison is the right approach or whether you need a different method entirely.

Frequently Asked Questions

Can I compare two sheets within the same Excel file?

Yes. Use the conditional formatting method, but reference the other sheet in the same file. For example, if you're on Sheet1 and comparing to Sheet2, the formula would be: =Sheet1!A1<>Sheet2!A1. You don't need to open a second file, and both sheets stay open automatically.

What if the two files have the same data but in different orders?

Sort both files by the same column first so the rows line up. Then use conditional formatting or Inquire. If the files are sorted differently on purpose and you need to compare them as-is, a text comparison tool will show you every line that differs, but you'll have to interpret the results manually.

Does conditional formatting work if one file is closed?

No. The formula needs both files open to work. If you close the file you're comparing to, the conditional formatting will show an error. Keep both files open while you're comparing, or use Inquire instead, which saves the comparison results in a new file you can review later.

Can I compare Excel files on a Mac?

Yes, but the Inquire add-in is not available on Mac. Use the side-by-side method or conditional formatting instead. If you need automatic comparison, export to CSV and use a web-based tool like Diffchecker that works on any computer.

What's the difference between comparing formulas and comparing values?

Conditional formatting and Inquire compare the actual cell contents, including formulas. If one file has =A1+B1 and the other has =A1+B1+C1, they'll be marked as different. If you only care about the calculated result, not the formula itself, you'll need to check manually or use a tool that shows values instead of formulas.