Convert a PDF to Grayscale

Every page is rendered, converted to grey and put back as an image. That makes colour printing costs predictable and often shrinks a scan considerably. It also means the pages stop being text, which is a real cost — worth accepting for a scan and rarely worth it for a document that was born digital.

Will my text still be searchable?

No. Pages become images. The tool warns you when the document had real text.

Does it make the file smaller?

Usually, for scans. For text documents it often makes them larger.

Can I just print in greyscale instead?

Often that is the better answer. Do this when the file itself needs to be grey.