Excel vs CSV: Which Export Format Should You Choose?

Table to Excel lets you export as Excel (.xlsx) or CSV (.csv). But which should you pick? In this deep dive, we'll explore the technical differences, data limits, and best use cases for each format to help you make the right choice.

The Short Answer

1. Excel (.xlsx) - The Rich Data Format

"Excel" files use the Microsoft Office Open XML format. It's actually a zipped archive of XML files that can store complex data structures.

✅ Pros

• Formatting: Preserves fonts, colors, cell width, and borders.
• Structure: Keeps merged cells (rowspan/colspan) intact.
• Multi-sheet: Can store multiple tables in separate tabs within one file.
• Data Types: Distinguishes between text, numbers, dates, and formulas.

❌ Cons

• Compatibility: Requires spreadsheet software (Excel, Numbers, LibreOffice) to open.
• Size: File size is larger due to XML overhead.
• Not Machine Readable: Harder for scripts or databases to parse without specific libraries.

2. CSV (Comma Separated Values) - The Universal Format

CSV is just plain text. Each line is a row, and columns are separated by commas. It's the "lingua franca" of data.

✅ Pros

• Universal: Opens in any text editor (Notepad, VS Code) and every spreadsheet app.
• Lightweight: Tiny file sizes since it stores only raw data.
• Database Friendly: The standard format for LOAD DATA INFILE (SQL) or database imports.
• Version Control: Great for Git as you can see line-by-line diffs.

❌ Cons

• No formatting: Bold text, colors, and merged cells are lost.
• Flat structure: Cannot handle multiple sheets or varying column counts easily.
• Encoding Issues: Can sometimes mess up special characters (e.g., é, ñ) without proper BOM (Byte Order Mark).

Technical Comparison: The Nitty Gritty

Feature	Excel (.xlsx)	CSV (.csv)
Max Rows	1,048,576	Unlimited (Text editor)
Max Columns	16,384	Unlimited
Filesize (10k rows)	~500 KB	~150 KB
Parsability	Requires Library (e.g., Pandas)	Native in all languages
Merged Cells	✅ Preserved	❌ Flattened/Split

Why CSV "Breaks" Merged Cells

A common user complaint is "My CSV export looks messy." This often happens with tables that use merged cells.

Example Table:

Category	Item A
	Item B

In Excel (.xlsx): The "Category" cell spans two rows, looking exactly like the web table.

In CSV: It becomes:

Category,Item A
,Item B

Notice the empty space? CSV has no concept of "spanning". This makes it look broken to humans, even though it's technically correct for data.

When to use which?

Scenario A: The Weekly Report

You need to send a sales report to your boss.
👉 Use Excel. You want the formatting, headers, and readability preserved.

Scenario B: The Database Migration

You are scraping a product list to import into a Shopify store or SQL database.
👉 Use CSV. Databases expect raw, clean data without styling overhead.

Scenario C: The "Backup"

You just want to save data for later.
👉 Use CSV. It's more likely to be readable by future software 10 years from now.