Convert XLS to ODS
The argument for this conversion is longevity. A .xls is a compound binary whose specification was reverse-engineered for years before it was published, and reading one in twenty years means finding software that still implements it. An ODS is a ZIP of XML against a published ISO standard, which anybody can open and inspect with ordinary tools.
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What it does
- Output is an inspectable ZIP of XML against a published standard
- Sheets, formulas and formatting are carried across
- Row ceiling rises from 65,536 to over a million
How to use XLS to ODS
- 1
Upload the .xls
Any legacy binary workbook, including ones written by software other than Excel.
- 2
The workbook is re-expressed as XML
Sheets, cells, formulas and styles are written into the OpenDocument structure rather than flattened to values.
- 3
Unzip it if you want to see inside
An ODS is a ZIP. Opening it with any archive tool shows the content XML, which is the whole point of the format.
How it works
The compound binary is opened and its workbook model — sheets, cells, formulas, number formats, styles — is written into the OpenDocument package. An ODS is a ZIP containing several XML parts, so the result is text describing a spreadsheet rather than a binary layout of one.
Formulas remain formulas and recalculate when opened. This is a re-encoding, not an export of values.
The longevity argument, concretely
A format is safe to archive when someone can open it without the software that wrote it. Unzip an ODS and the content XML is right there, tagged and legible. Open a .xls in a text editor and there is nothing a human can act on.
That difference is why retention policies at public bodies and universities increasingly name OpenDocument, and why "we still have the file" and "we can still read the file" are not the same claim for a proprietary binary.
What else improves
The row ceiling. The legacy format stops at 65,536 rows and 256 columns per sheet, and software that reaches it frequently truncates without complaint. OpenDocument has no comparable limit at that scale.
Macros also do not travel, which for an old workbook is usually a benefit rather than a loss.
What to check afterwards
Open the file once and recalculate. Formulas pointing at other workbooks by an old path are the common thing to fix, and they are far easier to spot now than when someone needs the number.
From a binary to something you can look inside
The practical difference is not what the spreadsheet does but what the file is.
An .xls is a proprietary binary structure that essentially requires Excel or a
compatible reader to make sense of. Its layout was reverse-engineered for years
before Microsoft documented it.
An ODS is a ZIP archive containing XML written against a published standard. Rename it, unzip it, and the content is there as text you can read, search and process with ordinary tools.
For an archive that has to remain readable in twenty years, that is the whole argument. A documented format that plain tooling can open does not depend on any one company continuing to ship a reader for it.
Examples
An archive migrating off proprietary binaries
The archive can now verify what is in the file with a text editor. That is not a convenience: it is the requirement that makes a format acceptable for long-term retention in the first place.
An old workbook near the row ceiling
The sheet was 600 rows from the legacy limit, where software tends to truncate silently rather than warn. The open format removes that cliff entirely.
Frequently asked questions
Why ODS rather than XLSX for an old workbook?
Both escape the binary and both remove the row ceiling, so the choice is about what the destination values. Choose ODS when a policy, an archive or a public body requires an open standard, which is the usual reason. Choose XLSX when the workbook will be used day to day in an organization running Excel, since it is what everyone there expects.
Can I still open the result in Excel?
Yes. Excel has read and written OpenDocument spreadsheets for many years, so nothing needs installing. Fidelity is good for the kind of workbook that exists as a .xls in the first place, since those predate almost every feature where the two formats diverge. Very complex conditional formatting is the one area worth checking.
What actually makes an open format better for archiving?
That its specification is published and the file is inspectable without the original software. An ODS unzips into XML that a person can read, so an archivist can verify what a file contains and, if necessary, recover it with ordinary tools. A compound binary offers neither of those, which is why retention policies increasingly name OpenDocument explicitly.