A4, Letter or the picture's own size: picking the page for an image PDF

Try the choices on your pictures

The Paper list has A4, US Letter, US Legal, A3, A5 and “Same as the picture”. Next to it, Orientation is Auto, Portrait or Landscape, and below, Margin (millimetres on every side) and Fit, Fill or Stretch. A4, Auto, 0 mm and Fit are the defaults.

The 2 kinds of choice

A fixed paper gives every page the same size, and each picture is scaled to fit inside it. A wide picture on a tall page leaves white above and below; a picture that matches the page’s shape fills it.

Same as the picture turns that round: each page takes its picture’s size and shape, edge to edge, so no page has a border and no picture is scaled. A set of mixed pictures makes a set of mixed page sizes.

A4 or Letter, in numbers

Letter is 5.9 mm wider and 17.6 mm shorter than A4. Printed on the other’s paper with the print dialog set to fit, an A4 page shrinks to 94 % on Letter and a Letter page to 97 % on A4. Nobody notices on a photo page; on a form with boxes to fill in, it is worth matching the reader’s paper.

A 12 megapixel photo (4032 by 3024 pixels) lands like this with Fit and no margin:

Every row keeps all 4032 by 3024 pixels, which is the point: on a fixed paper the question is layout, never quality.

Same as the picture: right for screens, odd at the printer

“Same as the picture” is the honest choice for screenshots, graphics and anything read on a screen: nothing is scaled, no border is added, and a viewer fits the page to the window. A 1920 by 1080 screenshot without a resolution note makes a page of 508 by 286 mm; the same file marked 144 dpi, 339 by 191 mm. Both look identical on screen.

The page size comes from the resolution written in the picture file, and 96 dpi when there is none. For photos this produces very large pages: a 12 megapixel photo whose file says 72 dpi becomes a page of 1422 by 1067 mm, and a HEIC photo, which carries no such note, 1067 by 800 mm. On screen that is invisible, because viewers zoom to fit. At the printer it is not: every page is a different, huge size, and the print dialog has to scale each one down onto the paper in the tray. For anything that might be printed, pick a fixed paper.

Orientation: let the page turn, or keep it upright

• Auto (the default) turns each page to match its picture: landscape photos get landscape pages and stay large.
• Portrait keeps every page upright. Wide photos then sit smaller, 210 by 157.5 mm on A4 instead of 280 by 210 mm, with white above and below. It reads better on a phone, where nobody wants to turn the screen, and it prints the same way up on every sheet.
• Landscape lays every page on its side, which suits a set of wide screenshots or slides.

Changing the page size afterwards

If the PDF is already made, or came from somewhere else, Resize PDF puts every page on A4, Letter, Legal, A3 or A5. Each page is scaled to fit and centred, keeps its way up (landscape pages go on landscape paper), and can get a Margin in millimetres. Pages are placed as they are rather than redrawn as pictures, so nothing is resampled.

What the page size setting does not do

• It never resamples the picture. All the pixels go into the PDF whatever the paper; the page size only says how large to draw them.
• It never crops with Fit. Only Fill cuts off what sticks out of the page (about 6 % of a 4:3 photo on A4), and only Stretch distorts. Fit, the default, shows everything.
• It cannot control a print shop. Their “fit to paper” or bleed settings may scale or trim the page later; ask them which size they want and give them exactly that.

The conversion runs on your device; nothing is uploaded. Next: choosing margins, why the conversion costs no quality, and printing a PDF the right size.