Save to PDF changes the size of the document

SAME!  I can't find much info anywhere on this issue, which I am having right now.  I am using "save as" and "save as a copy" to save a psd document as a pdf.  The document is 3488px x  1941px.  After saving as a pdf it is 837px x 466px.  Downsampling is OFF, compression is off.  WHAT is going on?  I saved several pdfs last night and they saved fine.  Tonight, I have no idea.  Would appreciate any help since I have to have these documents uploaded asap.  Thanks!

Which pdf settings are you using? 

What are the images’ resolutions? 

PDF files don't have a size in pixels, so any app or system that shows a width in pixels is simply wrong. They have a size in inches/mm only.

But we can perhaps help you discover what really happened. Where do you see the "size in pixels" exactly?

A PDF doesn't save pixels as such. It saves objects - IOW it treats everything as vector data with a certain physical size.

The Photoshop equivalent is smart objects, which honor physical print sizes, not pixel sizes.

The physical size is given by whatever ppi number is assigned (pixels per inch). Ppi is a formula to translate from pixels to print size, and vice versa.

If all ppi numbers are consistent all the way (in this case presumably 300 ppi), pixels should be preserved.

For all things weird in Photoshop try with preference reset Preferences in Photoshop (adobe.com)

Try using manual method to drag folder onto desktop then drag it back where it was if preference reset does not help.

Drag the entire Adobe Photoshop [Version] Settings folder to the desktop or somewhere safe for a back-up of your settings

Open Photoshop.