Answers
Short answer: To make an Excel sheet fit on one page as a PDF, open the Page Layout tab and, under Scale to Fit, set Width to 1 page while leaving Height on Automatic. That compresses only the width and lets the sheet run as many rows down as it needs. Then set the orientation to Landscape and trim the margins for a little more room before you export. The honest caveat: once a sheet has many columns, forcing it onto one page shrinks the text below readable, and at that point a multi-page layout with the header repeated on each page beats a single unreadable page.
Setting width only means Excel keeps the font readable as long as it can and simply adds pages downward, which is usually what people actually want.
There is a point where a wide table cannot be readable on one page. Squeeze twenty columns onto a single sheet and the text shrinks past the point anyone can read it, which defeats the purpose. Past roughly fifteen columns, a one-page PDF is usually a worse result than a clean multi-page one. The better move then is to let the table span pages and repeat the header row on each, so a reader can follow it.
If your sheets are routinely too wide to fit one readable page, CrazySmartPDF re-lays-out the sheet and is free to run on your own files. For the opposite problem, where Excel is shrinking text you did not want shrunk, see the guide on stopping the shrink.
How do I fit an Excel sheet on one page without it going tiny? Set Scale to Fit Width to 1 page and leave Height Automatic, then use Landscape and narrow margins. That compresses width only and keeps the font as large as it can, adding pages downward rather than shrinking everything.
Why does “Fit Sheet on One Page” make the text unreadable? That option forces both width and height onto a single page, so a large sheet is scaled down until it is tiny. Use the width-only setting, or accept a multi-page layout with repeated headers.
When should I not try to fit it on one page? When the sheet is wide enough that one page means unreadable text (often past around fifteen columns). A multi-page layout with the header repeated, or a converter that slices wide tables readably, gives a better result than a crushed one-pager.