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XLS
What is an XLS file?
The old binary Excel format, capped at 65,536 rows.
What XLS is
XLS is a binary format, meaningful only to a program that knows it. It is used for editing.
The extension is .xls, and the full name is Excel 97-2003 Workbook. Both matter less than what the file can hold, which is what the rest of this page is about.
Where XLS came from
Microsoft published it in 1987.
A format that has been readable for that long is a format worth trusting with something you want back in ten years.
The specification is published, but by its owner
It is written down and implementable, though the vendor decides what the next version looks like. In practice that is enough for the file to keep opening; it is not enough to be sure of it.
It is a legacy format
It still opens everywhere and is still written by older tools, but nothing new is being built around it. Convert what you mean to keep, and do not choose it for something starting today.
It can hold several pages in one file
A XLS file is not limited to one page, which matters when converting to something that is: a target that holds one image produces one file per page, and the numbering it chooses is worth checking before you send it on.
What kind of document it is
XLS holds a spreadsheet: cells, formulas and the sheets around them.
That is what decides how it converts: a spreadsheet becomes a print area, and a print area is a decision somebody has to make about where the columns break.
What opens XLS
Microsoft Excel and LibreOffice Calc read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
No browser reads it.
That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.
It is a working format
XLS is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.
The facts, in one place
| Extension | .xls |
|---|---|
| Media type | application/vnd.ms-excel |
| Published by | Microsoft |
| First published | 1987 |