Convert XLS to PDF

XLS is the binary format Excel wrote until 2003, which means a file with that extension is usually one you inherited rather than one you made: an accounts workbook from a predecessor, a price list from a supplier, a template that has been passed around an office for fifteen years.

Sending it on as an XLS asks a lot of the recipient. They need software that still opens the format, they will see whatever their own column widths and fonts produce, and they can change any number in it without leaving a trace. A PDF removes all three problems at once — it looks the same everywhere and it states rather than calculates.

This is the single thing that surprises people, and it is not a fault in the conversion. A sheet is an unbounded grid; it extends as far right as you keep typing. A PDF is made of sheets of paper with fixed edges. Somewhere between the two, a decision has to be made about where a page ends.

That decision is already stored in the spreadsheet — the print area, the orientation, the scaling, the repeated header rows — and the conversion follows it exactly rather than substituting its own judgement. A file that was never set up for printing converts as a file that was never set up for printing: columns spilling onto extra pages, or a wide table sliced down the middle.

Five minutes in a spreadsheet program prevents the most common disappointment. Switch the page orientation to landscape, set "fit all columns on one page" in the scaling options, define the print area to cover exactly the range you want, and set the header row to repeat so a long table stays readable on page four.

LibreOffice Calc does all of this and is free, so this is possible even without Excel. Then convert. The PDF that comes out will match the print preview you just looked at, because the conversion is doing the same thing the print preview was.

Every cell in the PDF shows the value it held at the moment of conversion. The formula behind it is gone, along with the links to other sheets and any external references. Nothing recalculates, and nothing changes if the file is opened in a different time zone or a different locale.

For the usual purpose — sending figures to a client, filing a statement, attaching accounts to an application — that is precisely what is wanted. If the recipient needs to work with the numbers, send the spreadsheet as well; a PDF is a statement, not a model.

Old XLS files are the classic carrier for spreadsheet macros, and a spreadsheet from an unfamiliar source is one of the more common ways an office network gets into trouble. A PDF cannot execute anything.

Converting therefore does two jobs at once: it fixes the layout and it strips the executable content, so the contents can be passed on without whatever was attached to them. If the macros are the point of the file, keep the original — but do not send it to people who only need to read the numbers.

The conversion runs a full office engine with metric-compatible substitutes for the common Windows fonts — Arial, Times New Roman, Courier, Calibri and Cambria among them. Metric-compatible means the substitute occupies the same space as the original, so column widths and line breaks land where they did.

An unusual font that is not embedded in the file is substituted with something similar, and there the layout can move slightly. Spreadsheets are more forgiving of this than documents, because the cell grid holds the structure regardless of what happens inside it.

Unlike the image conversions on this site, an office format needs a real office engine, and that runs on a server rather than in your browser. The XLS is sent over an encrypted connection, converted in an isolated environment with no route out to the internet, and the working files are deleted as soon as the job finishes.

The free limit is 25 megabytes per file, which is generous for a spreadsheet — an XLS is usually well under a megabyte unless somebody has pasted images into it.

If the goal is to modernise the file rather than to freeze it, PDF is the wrong target. Converting XLS to XLSX keeps every formula, chart and sheet, works in current Excel and in LibreOffice, and produces a considerably smaller file.

Use PDF when the spreadsheet is finished and is being sent, filed or printed. Use XLSX when it is still a working document that somebody will edit next week.