Turn any sheet of an .xlsx workbook into CSV, with real dates and one file per sheet. Runs on your device.
To convert an Excel file to CSV, choose the .xlsx file, pick a sheet, and press Download .csv or Copy CSV; a workbook with several sheets can also be downloaded as one zip with a CSV for each sheet. A .xlsx file is a zip of XML files. The tool opens that zip in your browser, reads the workbook, the shared strings, the cell styles and the sheet, and writes the cells as text. The page opens with a sample workbook of two sheets, so you can see the result before you add a file. In its Orders sheet, the first data row reads 1001, 2026-01-15, Ann Lee, 3, 19.99, TRUE, 59.97, and the cell "Bob, Jr." is put in quotes because it holds a comma. The CSV starts at cell A1 and every row is padded to the widest row, so the columns line up.
A date in Excel is a number, such as 46037, and a number format makes it look like a date. The tool reads the number format of each cell, and when it is a date or time format it writes 2026-01-15, 2026-02-03 14:30:00 or 14:30:00. Choose Excel numbers in the options to get 46037 instead. Both the 1900 and the 1904 date systems are handled, including Excel's fake day 29 February 1900. Other numbers are written as stored, to 15 significant digits, so 0.30000000000000004 reads 0.3; display formats such as percent, currency or a fixed number of decimals are not applied, so a cell showing 12.50% is written as 0.125. A formula cell gives the value Excel saved with it and is never recalculated, and the page counts any formula that has no stored value. A merged range is written in its top-left cell only, and the other cells are empty. Booleans are TRUE and FALSE, and an error cell keeps the error text Excel shows. Text that starts with = + - or @ gets a ' in front by default, so a spreadsheet that opens the CSV does not run it as a formula; numbers such as -3 are not changed, and the option can be turned off. A time format such as h:mm shows the time of day, so 1.5 reads 12:00:00; only a [h]:mm format counts past 24 hours.
The CSV uses a comma unless you choose a semicolon, tab or pipe, and a value is put in quotes when it contains the separator, a quote or a line break, with a quote inside doubled. Rows end with CRLF, as Excel writes them, or LF. The text is UTF-8. Excel usually reads a CSV as UTF-8 only when the file starts with a byte-order mark, so switch on Add a UTF-8 byte-order mark if the file is going back into Excel and has accented letters. Hidden sheets are listed in the picker and marked, and chart sheets are skipped.
The old .xls format is not supported, and neither is a workbook protected with a password, because both are a different container; open them in Excel and save a copy as .xlsx. The binary .xlsb format is not supported either. A file can be up to 40 MB, one sheet up to 100 MB of XML after unzipping and up to 3,000,000 cells, and the tool says when it stops early. Pictures, charts, comments, colours, column widths and formatting are not carried into a CSV, which holds only values.
The file is opened and read by code running in this tab, with no upload and no server that receives it. Only the four option choices are saved in this browser, never the file or its name. The page counts visits with Google Analytics, using the tool name and rough size groups such as 1 to 10 MB, never a file name, a sheet name or a cell.
Press Choose .xlsx file, pick the sheet, and press Download .csv. A sheet of 4 rows and 7 columns comes out as a 4-line file named like orders.csv. With several sheets, Download all sheets (.zip) gives one CSV per sheet.
Use Download all sheets (.zip). Each sheet becomes a file named after the workbook and the sheet, such as orders-Notes.csv, and hidden sheets are included. A CSV file holds one table, so one workbook cannot become one CSV.
Excel stores a date as a number of days, 46037 for 2026-01-15, and only the cell format makes it look like a date. This tool writes a date when the format is a date format. If you see the number, the cell has a general format; choose Excel numbers or fix the format in Excel.
Excel usually reads a CSV as UTF-8 only when it starts with a byte-order mark. Open CSV options and switch on Add a UTF-8 byte-order mark, then download again. Copy CSV always leaves the mark out.
No. Both are stored in an older container that this tool does not read, and it says so instead of guessing. In Excel, remove the password or use Save As, choose .xlsx, and add that copy.
No. The file is processed in your browser and not uploaded. Only your four option choices are saved in this browser, not the file or its name. The page counts visits with Google Analytics, using a size group such as 1 to 10 MB.