Excel vs CSV: Best File Format for Product Uploads

When you export a product catalog from one platform and prepare to import it into another, your first major decision is the file format: .xlsx or .csv? While both look like standard spreadsheets when opened on your computer, they are fundamentally different under the hood. Choosing the wrong format—or handling it incorrectly—is the single most common cause of dropped leading zeros on barcodes, corrupted accents or international characters, and failed batch imports.

Selecting the right format requires understanding how plain text and structured workbooks store data, how spreadsheet software interprets your numbers, and what your destination sales channel expects.

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What makes CSV files both powerful and risky

CSV (comma-separated values) is a plain text file format. The first row contains column headers, every subsequent row represents a distinct product record, and data fields are separated by a delimiter (usually a comma). CSV contains zero metadata: no cell colors, no formulas, no multiple tabs, no column widths, and no explicit data typing.

This extreme simplicity is CSV’s greatest advantage. Every operating system, database, and e-commerce platform can read plain text. A file with 50,000 product rows opens quickly and consumes very little memory. However, because a CSV file does not declare what kind of data is in each column, it introduces three major risks:

• Delimiter mismatch: While international standards use a comma, computers with regional settings (such as parts of continental Europe or Latin America) often export CSVs using semicolons by default. If your store software expects commas, a semicolon-separated file will dump every attribute into a single unreadable column.
• Character encoding errors: If a CSV is saved using ANSI, Windows-1252, or ISO encodings instead of UTF-8, characters with accents, umlauts, non-Latin scripts, or currency symbols become corrupted (often displaying as garbled text like é or “).
• Automatic number conversion: In a raw CSV, everything is text. But when you double-click a CSV to open it in Microsoft Excel, Excel tries to be helpful by guessing the data type. It automatically converts a 13-digit EAN barcode like 0850123456789 into the scientific notation 8.50123E+11 or strips the leading zero entirely (850123456789). Once saved, that barcode data is permanently altered.

How Excel XLSX files handle product data

An XLSX file is not a flat text file; it is an archived package of structured XML documents. Inside an XLSX file, every single cell explicitly declares its data type: string, number, boolean, date, or formula. The workbook also locks in character encoding and supports multiple worksheets within a single file.

Because XLSX preserves data types, a barcode column explicitly formatted as Text will remain text no matter how many times you open, edit, and save the workbook. Leading zeros stay intact, long serial numbers do not collapse into scientific notation, and international characters remain uncorrupted.

The trade-off is complexity. XLSX files are heavier to process, take longer to parse on servers, and are prone to template errors if sellers accidentally leave formulas, hidden rows, or merged cells in the sheet. For these reasons, many bulk-import engines strictly reject XLSX files in favor of CSV.

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What format do major e-commerce platforms require?

Platform requirements vary based on the architecture of their import tools. Before migrating products, check the target platform’s documentation:

• Shopify: Uses UTF-8 encoded CSV files for product imports and exports. Shopify relies on specific column headers (such as Handle, Title, Variant SKU, and Variant Price) and will reject multi-tab Excel files.
• WooCommerce: Features a built-in CSV product importer and exporter. While plugins exist to accept XLSX, the native core engine is built entirely around standard CSV files.
• Amazon: Uses tab-delimited text files (.txt) and category-specific Excel flat files (.xlsm or .xlsx) that contain built-in macros and data validation drop-downs.
• Regional Marketplaces: Platforms such as Trendyol (Turkey) or Otto (Germany) often provide sellers with category-specific Excel templates containing strict validation rules before allowing bulk catalog uploads.

If you are migrating products between ecosystems—such as moving from a marketplace Excel sheet to an independent store—you can convert your data using our Excel / CSV → Shopify tool. It maps custom supplier or marketplace columns directly to Shopify’s standard CSV schema in your browser without uploading your catalog to an external server.

Practical rules to prevent corrupted product uploads

Following a few operational practices will protect your inventory data across platform migrations:

1. Do not open raw CSV files by double-clicking: Opening a CSV directly in spreadsheet software triggers automatic type conversion. If you must inspect a CSV in Excel, use the Data > From Text/CSV import wizard, which allows you to explicitly mark SKU, UPC, and GTIN columns as Text before loading.
2. Do your editing in XLSX, then export to CSV: If you need to write formulas, calculate margin markups, or reorganize categories, work inside an Excel workbook where your text formatting is preserved. Once the edits are complete, export a fresh copy as CSV (UTF-8) for your final upload.
3. Normalize decimal separators: Ensure all prices use a consistent decimal point (19.99) rather than commas (19,99), unless your target platform specifically expects comma decimals based on store currency settings.
4. Verify image URLs before exporting: Make sure product image links point to publicly accessible HTTP/HTTPS URLs. If you are also updating product imagery, consider modern web standards as outlined in our guide on What Is WebP?.

Feature	CSV (.csv)	Excel (.xlsx)
File Type	Plain text	Compressed XML package
Data Types	Implicit (software guesses)	Explicit (stored per cell)
Preserves Leading Zeros	Only if imported carefully	Yes (when formatted as Text)
File Size	Very lightweight	Moderate to large
Platform Support	Universally supported (Shopify, WooCommerce)	Selective (Amazon flat files, regional templates)

More guides on this topic

This article is part of the E-commerce product files topic cluster. Other guides in the same cluster:

• How to Prepare a Product CSV File: Complete Guide — the pillar guide
• Export Trendyol Products to Excel: Step-by-Step Guide
• Hepsiburada Excel Template: How to Fill and Upload It

Frequently asked questions

Why did my barcodes lose their leading zeros after editing in Excel? Excel automatically treats strings of digits as numbers when opening a CSV file, dropping any leading zero because numbers do not require them. To prevent this, format the column as Text using Excel’s text import wizard rather than double-clicking the CSV file.

Can I upload an XLSX file directly to Shopify? No. Shopify’s native product importer requires a comma-separated CSV file encoded in UTF-8. You must convert or save your XLSX workbook as a CSV before importing.

What is the difference between standard CSV and CSV UTF-8? Standard CSV may save using your operating system’s default regional encoding (such as ANSI or Windows-1252), which breaks non-English characters. CSV UTF-8 uses universal Unicode encoding, preserving all international accents, special characters, and symbols.