CSV to Excel (XLSX) Converter

Convert single or multiple CSV files to Excel (.xlsx) workbooks in your browser. Preserves leading zeros, prevents garbled text, and merges CSVs into separate sheets.

How to Use
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Convert CSV to Excel (.xlsx) Without Losing Formatting

Drag and drop comma-separated CSV files to convert them into standard Excel workbooks (.xlsx) without opening Excel. Convert a single file, batch-convert multiple CSVs into separate .xlsx files bundled as a ZIP archive, or merge them into one Excel workbook with each CSV on its own sheet. The converter detects character encodings (UTF-8, UTF-16, Shift_JIS, and more) to prevent garbled characters, keeps leading zeros in ZIP codes and SKUs as text, and stops long numbers from turning into scientific notation. Everything runs locally in your browser, so your files are never uploaded to a server.

How to Convert CSV to Excel
STEP1

Select and Add CSV Files

Drag and drop your .csv files onto the page, or click "Choose Files" to select them from your device.

You can add multiple CSV files at once. Added files appear as cards under "File List" (supports up to 1,048,576 rows per file).

CSV File Upload Screen
STEP2

Choose Sheet Merging and Order

Turn on "Combine into One Excel File" to merge all uploaded CSVs into a single workbook (converted.xlsx), with each CSV placed on a separate worksheet tab. Drag the file cards to reorder how the tabs will appear.

Leave the switch off to convert each CSV into its own standalone .xlsx file.

Excel Conversion Options Screen
STEP3

Convert to Excel

Click "Convert to Excel" to generate and save your Excel file.

When converting multiple CSVs as separate files, all .xlsx workbooks are downloaded together in a single ZIP archive (csv_to_excel.zip).

Download Screen After Excel Conversion
Key Features & Specifications

Batch Convert Multiple CSVs to XLSX

Convert dozens of CSV files into standard .xlsx spreadsheets in one go. Skip Excel's Text Import Wizard, PowerShell scripts, or VBA macros.

Merge Multiple CSVs into One Workbook

Enable "Combine into One Excel File" to place each CSV onto a separate worksheet named after the original file. Drag and drop file cards to set the exact tab order.

Keep Leading Zeros & Stop Scientific Notation

Opening a CSV directly in Excel strips leading zeros (turning "00123" into "123") and converts 10+ digit numbers into scientific notation ("1.23E+12"). This tool formats zero-padded columns as text, preserves long numeric IDs, and keeps dates and multi-line quoted cells intact.

Auto-Detect Character Encoding

Detects UTF-8 (with or without BOM), UTF-16, Shift_JIS, EUC-JP, GBK, and Windows-1251 so international characters and symbols do not turn into garbled text.

Works on Mac, Windows, and Mobile Without Excel

Generate .xlsx files on any device with a web browser, even if Microsoft Excel is not installed. Output files open in Excel 2007+, Excel for Mac, Numbers, LibreOffice Calc, and Google Sheets.

Local In-Browser Excel Conversion

CSV parsing, formatting controls to prevent leading-zero drops, and .xlsx generation run entirely inside your browser. All processing completes locally on your device.

Common Use Cases

Consolidating Monthly or Regional CSV Exports into One Workbook

Combine separate CSV files into a single .xlsx workbook with individual sheets for each file, arranged in custom order via drag and drop.

Preserving ZIP Codes, Phone Numbers, SKUs, and Tracking IDs

Convert e-commerce orders, inventory feeds, and shipping CSVs without losing leading zeros in New England ZIP codes (e.g., 02115), phone numbers, or 12-digit UPC and tracking numbers.

Opening UTF-8 CSV Exports on Windows and Mac Without Garbled Text

Turn UTF-8 system exports from CRM, ERP, or database tools into ready-to-open .xlsx files that anyone on your team can double-click in Excel without encoding issues.

Replacing Repetitive VBA Macros, Python, or Power Automate Flows

Run recurring batch conversions in the browser without maintaining command-line scripts, Python pandas environments, or desktop automation workflows.

Frequently Asked Questions (FAQ)
How do I convert a CSV to Excel without losing leading zeros or getting scientific notation?
Drop your CSV into this converter and download the .xlsx file. The tool detects columns with leading zeros (such as "00123") and stores them as left-aligned text cells, while applying integer formatting to 10+ digit numbers so Excel does not display them as 1.23E+12.
How does the tool prevent garbled characters when converting CSV to XLSX?
Before building the Excel sheet, the converter inspects byte order marks (BOM) and character patterns to identify UTF-8, UTF-16, Shift_JIS, and other encodings. If a very small file is still misdetected, save the CSV as UTF-8 with BOM and upload it again.
Why did my CSV file fail to convert, and what is the maximum row limit?
Only files with the .csv extension are accepted, and each file can contain up to 1,048,576 rows (the maximum worksheet row limit in Microsoft Excel). The generated .xlsx files are compatible with Excel 2007 and newer, Excel for Mac, and Google Sheets.
Are my CSV files uploaded to an external server?
No. All CSV parsing and Excel file creation happen locally in your web browser. Your files are never sent to or stored on any server, making it safe for confidential business and financial records.
Why Choose This Tool?

Double-clicking a CSV in Excel often strips leading zeros, corrupts non-ASCII characters, and forces you to save files one by one. This browser-based converter turns single or multiple CSVs into formatted .xlsx workbooks, either as individual files or combined sheets, with zero server uploads.

Add your CSV files above to convert them to Excel.

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