LibreOffice (Windows / Mac / Linux)
ODS worksheets are documents in OpenDocument format, a “free” file type created to counter Microsoft's closed standards. The best known software they refer to are OpenOffice e LibreOffice: two open source productivity suites that allow you to do almost everything you do with Microsoft Office for free. They are compatible with all major operating systems (Windows, macOS and Linux) and - even more interesting - they are able to read and create documents in Microsoft Office format.
Between the two suites I suggest you try LibreOffice which was born more recently, is based on OpenOffice but includes some more functions than the latter and its development is generally more active. You can use it to open ODS documents without even the slightest compatibility problem and quickly save them as an XLS (or XLSX) file.
To download LibreOffice on your PC, connect to the suite's website and click on the button Download the version xx. When the download is complete, double-click on it to open the LibreOffice installation package (eg. LibreOffice_5.2.4_Win_x86.msi) and complete the setup by first clicking on Run and then NEXT twice in a row, Install, Yes e end.
If you use a Mac, you need to download LibreOffice by clicking the button first Download version xx e poi quello Translated user interface both present on the official website of the suite: the first is used to download the program installation package, the second the language pack necessary to translate the LibreOffice interface into cittàn (which on Windows is not necessary as it is included "as standard" in the software installation package).
Once the download is complete, open the LibreOffice installation package and drag the suite icon into the folder Applications of macOS. Then start LibreOffice by right clicking on its icon, selecting the item apri from the menu that appears and clicking on the button apri in the window that opens. This operation must be performed only at the first start of LibreOffice and serves to prevent macOS from preventing the execution of the software as it does not come from the Mac App Store or from developers "blessed" by Apple.
At this point, close LibreOffice (by pressing the key combination cmd + q on your Mac keyboard) and open the dmg package of the language pack. Right-click on the icon LibreOffice Language Pack, select the voice apri from the menu that appears and proceed with the installation of the long cittàn in LibreOffice by first clicking on the button apri e poi quello Install per due turn consecutive.
If you are told that you do not have permission to edit LibreOffice files, press the button Yes, identify me, type the password of your user account on macOS (the one you use to log in to the system) and press Submit.
Now we are! For transform ODS to XLS open the spreadsheet in ODS format by double clicking on it and, when LibreOffice starts, select the item Save with name from the menu Fillet.
Nella finestra che si apre, select the voice Microsoft Excel 97/2000 / XP / 2003 (.xls) from the drop-down menu for choosing the type of output file, indicate the folder in which to export the document and click on the button Save but I will complete the operation.
Please note: if double-clicking on the ODS file does not start LibreOffice automatically, right-click on the spreadsheet to convert to XLS and select the items Open with> LibreOffice Calc give the menu to compare.
Microsoft Excel (Windows / Mac)
If you have a copy of Microsoft Office on your computer (2007 SP2 version onwards), you can open spreadsheets in ODS format and export them to XLS or XLSX without much difficulty. With more elaborate documents there may be some minor compatibility issues, but generally things go well.
Then open Excel, click on the button Fillet collocato in alto a sinistra and selects the voice apri from the menu that opens. Then go up Shop by Department, set the option All files (*. *) from the drop-down menu at the bottom right and select the ODS document to open.
When the operation is completed, click on the button Fillet (top left), select the item Save with name from the menu that opens and go up Shop by Department, then set the option Excel 97–2003 Workbook from the menu Save eat, choose the folder in which to export the file and click on the button Save but I will complete the operation.
CloudConvert (Online)
It is possible too convert ODS to XLS through online services. One of the easiest to use is CloudConvert which works on any browser and does not require mandatory registration. It's free up to 25 conversions per day (of which a maximum of 5 at the same time) and has an upload limit of 1GB.
To use CloudConvert, connect to its home page and drag the ODS documents to be transformed into XLS onto the button Select files. Alternatively, click on the same button and choose the documents to convert "manually".
At this point, click on Start conversion and wait patiently for the spreadsheets to be transformed from ODS to XLS. Once the conversion is complete, you can download your spreadsheets one by one by clicking on the button Download that appears next to their names.
If you don't want to transform ODS files into XLS, but into XLSX, connect to this other CloudConvert page and follow the same procedure I just showed you for the ODS to XLS conversion.
ZamZar (Online)
Should CloudConvert not meet your expectations (or should it be temporarily unavailable), you can convert your ODS files to XLS using ZamZar.
If you have never heard of it, ZamZar is an all-in-one converter that allows you to convert Office documents, photos, videos, compressed archives, ebooks and many other types of files directly from the browser. It's completely free, supports the conversion of multiple documents in batches, and doesn't involve lengthy posting practices. However, it has an upload limit of 50MB and requires the entry of a valid email address, in fact the links to download the converted files are sent via email.
To convert ODS spreadsheets to XLS with ZamZar, connect to the main page of the service and drag the files to be converted into the field Step 1. Select quindi la voce xls from the drop-down menu Step 2, enter your e-mail address in the field Step 3 and click on the button Convert.
Within a few minutes you should receive e-mails with links to download the spreadsheets in XLS format. If you prefer XLSX format files to XLS, you can obtain this type of conversion by following the procedure described above and selecting the option xLSX from the drop-down menu Step 2. Easier than that?
How to convert ODS to XLS