CONVERTERS
CSV ↔ XLSX Converter
Move table data between CSV files and Excel workbooks, right in your browser.
SPREADSHEET FORMATS
Convert locally
Choose one .csv or .xlsx file, up to 25 MB. Files are read locally.
Use Windows-1252 for some older Windows exports with Western European characters.
Choose one worksheet. CSV files can contain only one table and do not store workbook formatting.
· worksheets found
Your selected files are processed in this browser and are not uploaded.
CSV and Excel workbook conversion
CSV is plain text containing one table. XLSX can contain multiple worksheets and richer spreadsheet data. This tool converts a CSV into a single-sheet workbook or exports one selected worksheet as CSV.
Quoting, separators, and encoding
Quoted commas, doubled quote marks, and line breaks inside quoted fields are preserved. CSV values stay as text when imported into XLSX; the converter does not guess whether a value should be a date, number, or formula. CSV input supports UTF-8 (with or without a BOM) and Windows-1252.
Worksheets and formulas
For XLSX to CSV, choose which worksheet to export. CSV cannot preserve multiple sheets, cell formatting, charts, or workbook features. Formulas are not calculated in your browser; formula expressions are exported as text prefixed with an apostrophe so they are not run as CSV formulas.
Browser limits
Files are limited to 25 MB, 20 worksheets, 50,000 rows per sheet, 256 columns, and 1,000,000 cells per sheet. Large workbooks can still use substantial memory. Macro-enabled .xlsm and legacy .xls files are not supported.
Frequently asked questions
Will numbers in a CSV become numbers in Excel?
No. CSV has no standard type information, so imported cells remain text rather than guessing at numbers, dates, or formulas.
Can I export every worksheet to a single CSV?
No. CSV represents one table at a time. Select one worksheet for each CSV export.
Are formulas recalculated?
No. Formula expressions are kept as plain text in the CSV output; this tool does not calculate spreadsheet formulas.
Are my files uploaded?
No. The locally bundled ExcelJS library reads and writes the selected files in your browser; the files are not uploaded.
This tool uses the locally bundled ExcelJS library; see the MIT license. Your files are not sent to NAB Tools.