Compare two CSV files for differences, by key column

Match the rows on a column that identifies each one, then compare the other columns row by row. A line-by-line diff breaks as soon as one file is sorted differently or has one extra row.

1. Pick the match column: SKU, item number, customer name, email or ID.
2. Rows with a match in both files are changed or unchanged.
3. Rows with no match are only in A or only in B.
4. For numbers, change % = (new value − old value) ÷ old value × 100.

Example: SKU AB-1001 cost 42.50 in the old list and 46.75 in the new one. (46.75 − 42.50) ÷ 42.50 × 100 = a 10.0% increase.

Put the new list in one sheet and the old list in another, then look up each SKU’s old price next to its new price. In Excel for Microsoft 365, 2021 or 2024:

• Old price: =XLOOKUP(A2, Old!A:A, Old!C:C, "Not found")
• Change %: =(C2-D2)/D2, formatted as a percentage
• Excel 2016 or 2019: =VLOOKUP(A2, Old!A:C, 3, FALSE) in place of XLOOKUP

“Not found” marks new items. Repeat the lookup the other way round to find items that were dropped.

Example: new cost 6.60 in C2, old cost 6.25 in D2. (6.60 − 6.25) ÷ 6.25 = 5.6%.

The tool above does both directions at once and gives you the count that went up and down for each column. Updating the prices afterward is a bulk edit, covered in our guide to bulk editing Shopify prices.

Microsoft’s Spreadsheet Compare shows two workbooks side by side and colors the cells that differ. It is only in Excel for Windows, in Microsoft 365 Apps for enterprise and equivalent editions.

On any other setup, save each sheet as CSV, or copy the cells and paste them into the boxes above. The “Changed” tab lists every field that differs, with both values, and the download opens in Excel.

• QuickBooks Online: Reports > Standard reports, open your customer list report, then Export/Print > Export to Excel. Save it as CSV. The title rows at the top are skipped.
• HubSpot: Contacts or Companies > Export, CSV format. HubSpot emails you a download link.
• Shopify: Products > Export > CSV for Excel. An export of all products is emailed to you.
• Any spreadsheet: File > Save As > CSV, one row per record, with a header row.

It cleans the match column before matching: capital letters and extra spaces are ignored. For customer lists it also drops Inc, LLC, Co and punctuation, and reads “&” as “and”. For SKU and price lists it ignores leading zeros, which Excel often strips.

Values are compared the same careful way:

• amounts: “51.00”, “51” and the same amount with a dollar sign are equal
• phone numbers: “(773) 555-0199” and “773.555.0199” are equal
• dates: “11/01/2026”, “2026-11-01” and “Nov 1, 2026” are equal
• text: equal when only capitals or spacing differ

Example: “Acme Supply Co.” in the CRM and “Acme Supply, Inc” in QuickBooks both become “acme supply” and match. For names spelled differently, such as “Riverbend Property Grp”, use fuzzy match two lists.