How To Compare Two Spreadsheets Side by Side

The fastest way to spot differences between spreadsheets

The simplest method is to open both spreadsheets in separate windows and arrange them side by side on your screen. In Excel, Google Sheets, or LibreOffice Calc, you can open the first file, then open the second file in a new window, and drag each window to take up half your screen. This works best when the spreadsheets are small or when you already know roughly where the differences are.

If the spreadsheets are large or the differences are scattered throughout, side-by-side viewing becomes tedious quickly. In that case, you will want to use a built-in comparison tool or a formula-based approach depending on which program you are using.

Key Takeaways

Excel has a built-in compare tool under the Review tab that highlights differences automatically, though it works best when both files have the same structure.
Google Sheets does not have a native comparison tool, but you can use a formula like COUNTIF to flag rows that appear in one sheet but not the other.
LibreOffice Calc offers a comparison feature under Tools > Compare Document that works similarly to Excel's approach.
If you need to find exact matches or differences in specific columns, a VLOOKUP or INDEX/MATCH formula will show you which rows exist in one file but not the other.
For very large files or complex comparisons, exporting both spreadsheets as CSV and using a dedicated diff tool outside the spreadsheet program is often faster and more reliable.

Using Excel's built-in comparison feature

Excel's compare tool is the fastest option if both spreadsheets have the same column structure. Open the first spreadsheet, then go to the Review tab at the top of the screen. Click "Compare" (in some versions it may say "Compare and Merge Workbooks"). A dialog box will open asking you to select the second file to compare against.

Excel will then highlight cells that differ between the two files. Cells with changes appear with a colored border, and Excel creates a summary sheet listing every difference it found. This method works well when you are comparing versions of the same file — for example, a budget spreadsheet from last month versus this month.

The limitation is that Excel's compare tool assumes both files have identical row and column layouts. If one file has extra rows or columns, or if the data is sorted differently, the comparison will not work correctly. In those cases, you will need to manually align the data first or use a formula-based approach instead.

Finding differences in Google Sheets with formulas

Google Sheets does not have a built-in compare feature, but you can create one using formulas. The most common approach is to use COUNTIF to check whether each row in one sheet exists in another sheet. Open both spreadsheets in separate tabs within the same Google Sheets file, or keep them open in different browser windows.

In a new column in the first sheet, enter a formula like =COUNTIF(Sheet2!A:A, A1). This formula checks whether the value in cell A1 appears anywhere in column A of Sheet2. If the result is 0, that row exists in Sheet1 but not in Sheet2. If the result is 1 or higher, the row exists in both sheets. Copy this formula down the entire column to check every row at once.

For a more detailed comparison, use VLOOKUP or INDEX/MATCH to pull the corresponding value from the second sheet into a new column, then use a straightforward IF statement to flag whether the values match. For example: =IF(A1=VLOOKUP(A1, Sheet2!A:B, 2, FALSE), "Match", "Difference"). This approach takes longer to set up but gives you exact information about which cells differ and by how much.

Comparing spreadsheets in LibreOffice Calc

LibreOffice Calc has a comparison feature similar to Excel's. Open the first spreadsheet, then go to Tools in the menu bar and select "Compare Document". A file browser will open where you can select the second spreadsheet to compare against.

LibreOffice will highlight differences with colored backgrounds and create a summary of changes. Like Excel, this works best when both files have the same structure. If the files have different layouts, you will need to reorganize them first or use a formula-based method instead.

Using formulas to match rows across two spreadsheets

When you need to find which rows exist in one spreadsheet but not the other, a VLOOKUP formula is the most straightforward approach. Assume you have a list of customer IDs in column A of Sheet1 and a different list of customer IDs in column A of Sheet2. You want to know which customers appear in Sheet1 but not in Sheet2.

In a new column in Sheet1, enter =IFERROR(VLOOKUP(A1, Sheet2!A:A, 1, FALSE), "Not Found"). This formula looks for the value in A1 within Sheet2's column A. If it finds a match, it returns the value. If it does not find a match, it returns "Not Found". Copy this formula down for every row in Sheet1. Any row that shows "Not Found" exists in Sheet1 but not in Sheet2.

To find the reverse — rows that exist in Sheet2 but not in Sheet1 — repeat the same process in Sheet2 using a VLOOKUP that references Sheet1. This two-way check shows you the complete picture of what differs between the two files.

Exporting to CSV and using a dedicated diff tool

For very large spreadsheets or complex comparisons, the fastest approach is often to export both files as CSV (comma-separated values) and use a dedicated comparison tool outside the spreadsheet program. CSV is a plain-text format that most comparison tools can read.

To export as CSV in Excel, Google Sheets, or LibreOffice, go to File > read As (or Save As) and select CSV format. Then read a free diff tool like WinMerge (Windows), Meld (Linux), or DiffMerge (Mac and Windows). Open both CSV files in the diff tool, and it will show you every line that differs between the two files, with color coding to highlight additions, deletions, and changes.

This method is especially useful when you are comparing data that has been sorted differently or when the spreadsheets have different numbers of rows. A diff tool does not assume any particular structure — it straightforward compares the files line by line and shows you exactly what changed.

Checking for duplicate rows within a single spreadsheet

Sometimes you need to compare a spreadsheet against itself to find duplicate rows. In Excel, select all the data you want to check, go to the Data tab, and click "Remove Duplicates". Excel will show you how many duplicate rows it found and remove them. If you want to see which rows are duplicates before removing them, use conditional formatting instead: select your data, go to Conditional Formatting > Highlight Cell Rules > Duplicate Values.

In Google Sheets, select your data and go to Data > Data Cleanup > Remove duplicates. Google Sheets will remove exact duplicate rows and show you a summary. For more control, use a formula approach: add a helper column with =COUNTIF($A$1:A1, A1) and copy it down. Any row where this formula returns a number higher than 1 is a duplicate.

Frequently Asked Questions

Can I compare two spreadsheets that have different column orders?

Yes, but you will need to reorganize one of them first or use a formula-based approach. Built-in comparison tools like Excel's Review > Compare assume the columns are in the same order. If your columns are in different orders, rearrange one file to match the other, then run the comparison. Alternatively, use VLOOKUP or INDEX/MATCH to pull data by column name rather than position.

What if one spreadsheet has more rows than the other?

Built-in comparison tools will flag all the extra rows as differences. A formula-based approach using VLOOKUP or COUNTIF is better in this case because it will show you exactly which rows are missing from the shorter file. You can then decide whether those rows should be added or whether the difference is expected.

How do I compare two spreadsheets if they have different data types in the same column?

Comparison tools may not recognize matches if one column contains numbers stored as text and the other contains actual numbers. Before comparing, convert both columns to the same data type. In Excel or Google Sheets, you can use the VALUE function to convert text to numbers, or TEXT to convert numbers to text. Then run your comparison again.

Is there a way to compare spreadsheets without opening them both at the same time?

Yes. Export both files as CSV, then use a dedicated diff tool like WinMerge or Meld. These tools let you open one file, then select the second file to compare against, so you do not need to have both open in your spreadsheet program. This approach also tends to be faster for large files because diff tools are optimized for line-by-line comparison.

Can I automate spreadsheet comparisons so they run on a schedule?

Yes, but it requires scripting or a third-party tool. In Google Sheets, you can write a Google Apps Script that compares two sheets and sends you an email with the results. In Excel, you can use VBA macros to automate comparisons. For a simpler approach, use a dedicated diff tool from the command line with a scheduled task (Windows) or cron job (Mac/Linux) to run comparisons automatically at set times.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.