XLS to PDF

The binary format was replaced by .xlsx in 2007, but it never went away. Banks, payroll systems, government portals and older accounting software still export it, because it was the interchange format for a decade and everything can read it.

Reading it is a different job from reading a .xlsx: the old file is an OLE compound document containing BIFF records rather than a ZIP of XML. Both are handled here, and the format is detected from the file's own bytes — so a .xls that is really a .xlsx, or the other way round, still converts.

This is the part every converter glosses over. Excel does not store pages — it stores a grid — and turning a grid into pages is a series of decisions. That is why Excel itself asks you about print areas, scaling, page order and repeated header rows before it will print.

Here those decisions are made the predictable way: every row, in order, in equal-width columns, each cell wrapped rather than cropped. Sheets start on a new page and are labelled. Nothing is cut off, and nothing is silently dropped.

What does not come across: colours, fonts, borders, cell shading, conditional formatting, merged cells, frozen panes, charts, images and comments. Those are presentation, and reproducing them means reimplementing Excel's renderer. What you get is the content, set out as a readable table.

A workbook stores two things for every calculated cell: the formula, and the value Excel last worked out for it. The PDF gets the value, because a PDF has nowhere to put a formula.

Almost always that is what you want. The exception is a workbook edited by something that did not recalculate before saving — some export tools, and some scripts — where the stored value can be stale. If a number looks wrong, open the file in Excel, let it recalculate, and save again.

Dates come across as they are formatted in the sheet, not as the underlying serial numbers, so a cell showing 2024-03-01 does not become 45352.

PDF has fourteen built-in fonts that every reader already has, and they cover WinAnsi — Latin letters, accented European characters, curly quotes, the euro and pound signs. Nothing else.

Writing Chinese, Japanese, Korean, Arabic, Hebrew, Thai, Devanagari or Cyrillic means embedding a font that contains those glyphs, and a font with usable CJK coverage is several megabytes. Downloading that on the chance a visitor needs it is not a reasonable trade for a page that mostly converts English.

So instead of producing a document full of blank boxes, unencodable characters become a question mark and the conversion tells you exactly how many were affected and which script they belonged to. If your text is in one of those scripts, this is the wrong tool and you should use a desktop converter — that is a more useful answer than a broken file.