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XLS to XLSX converter

Turn an old Excel .xls file into an .xlsx. Every sheet comes across with its data, and your file never leaves your browser.

Works with
XLSXLSX
Opens inExcelGoogle Sheets

Drop an .xls file here

An Excel 97-2003 .xls workbook, up to 100 MB. It stays on your computer.

  • No sign-up
  • Nothing uploaded
  • Every sheet kept
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What you get

Your old workbook, as a current Excel file.

  • Your file stays on your computer

    The .xls is read and the .xlsx is built in your browser. Nothing is sent to Mammoth or anyone else.

  • Every sheet, in order

    A workbook with five sheets becomes an .xlsx with the same five, under the same names.

  • The data, not the formatting

    Text, numbers, dates and formula results come across. Formulas, colours and charts stay in the old file.

How it works

How to convert XLS to XLSX

Every value lands in the cell it had, on a sheet with the same name. Numbers stay numbers and dates stay dates.

  1. 1

    Add your .xls file

    Drop the file on the box or choose it. A workbook from Excel 97 to 2003 works.

  2. 2

    Check the sheets

    A preview shows each sheet. Pick one from the menu to see the others.

  3. 3

    Download

    Save one .xlsx with every sheet, or one sheet on its own.

Your options

Other ways to do it

Excel itself does this best if you have it. Without Excel, the choice is between uploading the file and converting it here.

  • Excel's Save As

    You have Excel and need the formatting

    • No Excel neededNo
    • Every sheet at onceYes
    • Keeps formulas and formattingYes
    • Nothing uploadedYes

  • Online converters that upload

    A file with nothing private in it

    • No Excel neededYes
    • Every sheet at onceYes
    • Keeps formulas and formattingPartly
    • Nothing uploadedNo
  • This page

    This converter

    The data, without Excel or an upload

    • No Excel neededYes
    • Every sheet at onceYes
    • Keeps formulas and formattingNo
    • Nothing uploadedYes
In Excel itself

How to convert XLS to XLSX in Excel

If you have Excel, Save As makes an .xlsx that keeps the formulas and formatting too.

orders.xlsCompatibility Mode
File › Save As
File nameorders.xlsx
Save as typeExcel Workbook (*.xlsx)

Need a CSV instead? The Excel to CSV converter reads .xls files too.

  1. 1

    Open the .xls in Excel. The title bar says Compatibility Mode.

  2. 2

    Go to File > Save As and choose where to save.

  3. 3

    Set Save as type to Excel Workbook (*.xlsx).

  4. 4

    Select Save. The .xls stays as it was, next to the new .xlsx.

Your file stays private

The converter runs inside this page. Your workbook is read and rebuilt as an .xlsx on your computer, and nothing is sent to Mammoth. That makes it safe for finance files and anything with customer data in it.

How we handle your data

Once the page has loaded, it works with your internet switched off.

Every month

Getting the same workbook every month?

Mammoth can take it from there. Put each month's workbook in a folder as .xlsx, and the rows are added to one table.

Try Mammoth free

Monthly workbooks

Augustorders-aug.xlsx
Septemberorders-sep.xlsx
Octoberorders-oct.xlsx
DriveDropboxOneDriveSFTP
All monthsUp to date
AugNorth1,284
AugSouth962
SepNorth1,310
SepSouth1,005
OctNorth1,198

Illustration. Every new file in the folder is added to the same table.

Questions

XLS to XLSX questions

What comes across to the .xlsx?
Every visible sheet, in order, with its text, numbers, dates and TRUE/FALSE values. A formula gives the result Excel last calculated. The formulas themselves, cell formatting, column widths, charts and macros are not copied. If you need those, open the file in Excel and use Save As.
Does the layout stay the same?
Yes. Every value lands in the same cell it had in the old file, so title rows, blank rows and notes under a table stay where they were. A merged cell is unmerged, with its value in the first cell.
Is my file uploaded anywhere?
No. The page reads the .xls and builds the .xlsx inside your browser. Once the page has loaded, it works with your internet switched off.
Are dates still dates?
Yes. A date is read from the cell's number format and written as a real Excel date, so it still sorts and filters as one.
What happens to hidden sheets?
They are left out, along with chart sheets. Every sheet you can see in Excel comes across.
Can it open a password-protected .xls?
No. The page tells you when a file is protected. Open it in Excel, remove the password, and try again.
Does it work with files from Excel 95 or older?
No. It reads the .xls format used by Excel 97 to 2003. An older file gets a message saying so.
Can I get a CSV instead?
Yes. The Excel to CSV converter reads .xls files too, and saves one sheet or every sheet as CSV.
Is it free?
Yes, with no account and no email.

More free tools

Free toolODS to ExcelTurn a LibreOffice spreadsheet into an .xlsx.Take a lookFree toolExcel to CSVSave one sheet or every sheet as CSV.Take a lookFree toolMerge Excel filesCombine several workbooks into one.Take a look