CSV to XLSX Converter

Turn a CSV export into a real Excel workbook without the damage a double-click does: ZIP codes keep their zeros, long order numbers keep every digit, and names in any language read correctly.

or drop CSV, TSV, TXT … files here ·

Max 95 MB per file· Up to 20 files· Deleted after 30 minutes

Output

Convert to

Files are processed on our servers and deleted after 30 minutes.

How to use this tool

1
Upload the CSV files
Drop .csv, .tsv or .txt exports onto the upload area, up to 20 per batch and 95 MB each. Delimiter is set to Auto detect, so comma, semicolon and tab files all work.
2
Confirm the header row
First row is header is on, so row 1 becomes the column titles. Turn it off if the file starts directly with data, and set Sheet name if the tab should not be called Sheet1.
3
Convert and download
Press Convert to XLSX (Excel) and open the workbook in Excel, Google Sheets, Numbers or LibreOffice.

Answer

What is the safest way to convert CSV to Excel?

Convert the file instead of double-clicking it. Upload the CSV and press Convert to XLSX (Excel): the delimiter is detected, the first row becomes headers, numbers become numeric cells, and values that would be damaged, such as 00125 or a 16-digit ID, are stored as text.

What a CSV to Excel converter has to protect

A CSV file has no types: every field is text, and RFC 4180 only says how fields are separated and quoted. When Excel opens one directly, it decides for each cell whether the text is a number, a date or a formula. Most of the time that guess is right; the exceptions are the data people care about most.

Excel keeps 15 significant digits, so a 16-digit card or tracking number ends in 0. Values with leading zeros, such as ZIP codes 02134 or SKUs 00125, become plain numbers. Text like 1-2 or MARCH1 becomes a date. A UTF-8 file without a byte order mark is read in the Windows code page, so São Paulo shows as SÃ£o Paulo. The sample below contains three of these traps.

CSV input with values Excel usually changes

sku,zip,phone,ordered,tracking,city
00125,02134,+1 617 555 0142,2026-03-04,9400111202555842761234,São Paulo
00981,07030,+1 201 555 0187,2026-03-05,9400111202555842769876,Hoboken

CSV vs XLSX: what each format can hold

from ↓ · to →	Cell types	Several sheets	Formulas	Formatting	Over 65,536 rows	Readable in any text editor
CSV	– CSV to Cell types: no	– CSV to Several sheets: no	– CSV to Formulas: no	– CSV to Formatting: no	CSV to Over 65,536 rows: yes	CSV to Readable in any text editor: yes
XLSX	XLSX to Cell types: yes	XLSX to Several sheets: yes	XLSX to Formulas: yes	XLSX to Formatting: yes	XLSX to Over 65,536 rows: yes	– XLSX to Readable in any text editor: no
XLS	XLS to Cell types: yes	XLS to Several sheets: yes	XLS to Formulas: yes	XLS to Formatting: yes	– XLS to Over 65,536 rows: no	– XLS to Readable in any text editor: no

supported not offeredWhat each format can hold. Converting CSV to XLSX gains typed cells and room for formatting; it cannot invent formulas the CSV never had.

CSV

Comma-separated values

CSV is a plain-text format for tables in which each line is a row and commas separate the columns. It has been used since the early days of computing and is described in RFC 4180, though many variants use semicolons or tabs and different text encodings. Nearly every spreadsheet, database and analytics tool can import and export it, which makes it the default format for moving data between systems. CSV stores only values, with no formulas, formatting, multiple sheets or data types.

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CSV converter

XLSX

Microsoft Excel workbook

XLSX is Microsoft Excel's default workbook format since Office 2007, based on the Office Open XML standard. It stores multiple sheets, formulas, formatting, charts, pivot tables and data validation in a ZIP package of XML. It supports over a million rows per sheet and is the default exchange format for business spreadsheets. Google Sheets, LibreOffice and Numbers open XLSX, though macros and advanced features may not carry over.

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Introduced: 2007 · Microsoft

XLSX converter

CSV turns into XLSX when exported data is handed to people: a report for a manager, an order list for a client, survey results for a team, all of whom expect a workbook with typed cells and a sheet name, not raw text.

Convert CSV to XLSX: what the workbook looks like

In the converted file, sku, zip and tracking are text cells, so 00125 and the 22-digit tracking number appear exactly as in the CSV. The ordered column holds ISO dates, which Excel recognizes as dates you can sort and filter by month. City names keep their accents, because the file is read as UTF-8 regardless of what the CSV's author used to save it.

The workbook gets one sheet, named Sheet1 unless you change Sheet name (31 characters at most, the same limit Excel enforces). Column formatting is left plain so the receiving person can apply their own number formats. If the recipient runs Excel 2003 or an old import system that refuses XLSX, CSV to XLS writes the older binary format instead.

Do not round-trip the workbook through CSV again in Excel

Once the XLSX is correct, keep working in it. Saving it back to CSV from Excel and reopening the CSV by double-click reintroduces every conversion problem above. When a system needs CSV again, export a fresh copy with XLSX to CSV.

CSV to XLSX FAQ

Why not just open the CSV in Excel and save it as XLSX?

Because Excel converts the values while opening, before you get the chance to save. Leading zeros, long numbers and anything resembling a date are changed in memory, and saving as XLSX makes those changes permanent. Converting first, without Excel guessing, keeps the original text.

Does the XLSX file come out smaller than the CSV?

Often, yes. XLSX is a ZIP archive, and repeated text such as country names or status values is stored once in a shared string table, so exports full of repeated values usually shrink.

My CSV has more than a million rows. What happens?

An Excel worksheet stops at 1,048,576 rows, including the header. Excel itself shows a "file not loaded completely" warning for such files. Split the CSV first, or load it into a database with CSV to SQL where row counts do not matter.

Can Excel stop changing my data by itself?

Recent builds of Excel for Microsoft 365 have Automatic Data Conversion options under File → Options → Data, where you can switch off removing leading zeros, converting long numbers and turning text into dates. Older versions have no such switch, which is why converting outside Excel is the safer route.

Which delimiter does Auto detect recognize?

It checks the first lines for commas, semicolons, tabs, pipes and spaces and picks the one that splits every line into the same number of fields. If the columns look wrong, set Delimiter by hand and convert again.

Will Google Sheets open the XLSX as well?

Yes. Upload it to Google Drive and open it with Google Sheets, or import it into an existing sheet. Keep in mind that a Google spreadsheet is limited to 10 million cells in total across all its tabs.