How do I convert CSV to XLSX?

Paste your CSV or drop a .csv file. Select the delimiter (comma, semicolon, tab, or pipe), pick a sheet name, then click "Convert to XLSX". Download a proper Excel workbook ready to open in Excel, Google Sheets, or Numbers.

Why use this instead of opening CSV directly in Excel?

Opening CSV directly in Excel can remove leading zeros, round long identifiers, or interpret date-like text. This converter assigns cell types before Excel opens the file: ordinary numbers can be numeric, while leading-zero values, long IDs, and dates remain text. Choose "Keep all values as text" when you want every field stored as text.

Are numbers properly typed in the output?

Ordinary numbers are stored as numeric cells only when their decimal representation can be preserved within Excel's 15-significant-digit precision. Safe decimals such as 89.50 stay numeric with a number format that keeps the decimal places. Leading zeros, long identifiers, and precision-sensitive decimals stay as text. Date-like values also stay as text; this tool does not create typed date cells. You can keep all values as text instead.

Can I name the sheet?

Yes. Set the sheet name in the settings panel; the default is "Sheet1". Each conversion creates a new workbook with one worksheet. Converting another CSV does not add a sheet to a previous workbook. Excel sheet names are limited to 31 characters and cannot contain : \ / ? * [ or ].

Is my CSV data uploaded?

No. The conversion runs entirely in your browser using SheetJS. Your data never leaves your device.

CSV to Excel Converter — Create XLSX Online

CSV input

Drop a file, paste, or type. Processed locally — never uploaded.

Settings

CSV delimiter

Sheet name

Max 31 characters. Avoid / \ ? * : [ ].

First row is header

Header labels are stored as text, including numeric labels.

Keep all values as text

Otherwise, safe numbers stay numeric with their decimal places. Long IDs and leading zeros stay text.

Trim whitespace around values

Add CSV or choose a file to convert.

Excel file will be ready here

Paste CSV or drop a file, then click Convert

How it works

4 steps. Everything runs in your browser.

Paste CSV

Paste your CSV data, drop a .csv file, or type directly.

Configure

Choose the delimiter, set a sheet name, and decide whether to keep all values as text. Mark the first row as headers if appropriate.

Convert

Build a one-sheet .xlsx workbook locally. Safe numeric values become numbers; identifiers and date-like values stay text.

Download

Get the .xlsx file ready to open in Excel, Google Sheets, Numbers, or LibreOffice Calc.

Why not just rename the .csv extension to .xlsx?

Renaming doesn't work — CSV is plain text, XLSX is a zipped XML archive. Excel will show a format mismatch warning for a renamed file. You need a conversion that builds a valid XLSX structure with cell types, sheet metadata, and shared strings.

This tool uses SheetJS to construct a native XLSX workbook from your CSV input. The output is an .xlsx file with numeric cells for safe ordinary numbers, and text cells for values such as ZIP codes, long account numbers, and date strings. CSV contains no styling, so the result starts as a plain worksheet that you can format in Excel.

The leading-zero problem (and why this tool fixes it)

When you open a CSV directly in Excel, the cell "012345" (e.g., a ZIP code) is automatically converted to the number 12345 — the leading zero is silently lost. This tool detects values that start with a zero and stores them as text in the XLSX, so the zeros remain intact. Long identifiers are also stored as text to prevent rounding. For codes that do not have leading zeros, use "Keep all values as text" to prevent them from becoming numeric cells. Turn off "Trim whitespace" when surrounding spaces are meaningful.

Example: preserve account IDs and dates

Paste this comma-separated example, keep the first-row header option enabled, and convert:

account_id,zip,quantity,invoice_date
12345678901234567890,01234,12,2026-09-01

The account ID, ZIP code, and date are text cells; quantity is the number 12. The date remains the string 2026-09-01, so date arithmetic requires a separate conversion in Excel. With "Keep all values as text" enabled, quantity is text too.

Before you convert

Use UTF-8 input and select the actual delimiter. Semicolon-separated CSV needs the semicolon option.
Each conversion makes a separate workbook with one sheet; it does not merge CSV files.
CSV formulas are stored as text. The converter does not evaluate formulas or infer dates.
File uploads are limited to 50 MB. Large exports also depend on available browser memory.

Common use cases

Database export

PostgreSQL/MySQL → CSV → XLSX for ad-hoc analysis in Excel.

API output to spreadsheet

Convert REST API CSV downloads to a workbook for finance teams.

Bulk delivery

Send CSV reports to non-technical recipients as familiar .xlsx attachments.

Account identifiers

Keep long account numbers and leading-zero codes intact as text cells.

Named reports

Create a new one-sheet workbook with a descriptive worksheet name.

Pipe-delimited data

Convert legacy mainframe/EDI exports (pipe-delimited) to Excel-ready XLSX.

Why use our CSV to XLSX converter?

100% private

CSV parsed and XLSX built entirely in the browser. No upload, and analytics do not receive your spreadsheet content.

Control cell types

Keep long IDs and leading zeros as text, with an option to store every value as text.