Flip PDF pages into a mirror image

A PDF has no “mirror” setting, so the page’s existing drawing is wrapped rather than rewritten: a mirror instruction is put in front of everything the page already draws, and closed off after it. Nothing inside is parsed, moved or re-encoded, which is the only way to reverse a page without putting its fonts and images at risk. The words come out reading backwards, which is exactly what transfer paper and screen printing want, and never what a sideways scan wants.

Comments, highlights, links and form fields are not mirrored. They sit beside the page’s drawing rather than inside it, so they stay exactly where they were — the result says how many pages that affected, and remove annotations will strip them if they are in the way.

Mirror the pages

No account. Your upload is deleted after 2 hours, the result after 24 hours.

How it works

  1. Choose the axis. Left to right swaps the two sides of the sheet and is what almost everyone means by a mirror image. Top to bottom swaps the head and the foot, which reads as upside down and back to front at the same time.
  2. Name the pages, or take them all. Artwork is usually one page. A document scanned through the back of the paper is usually every other page, so ‘odd’ or ‘even’ does it in a single run.
  3. Check it against the original. Open the result beside the source. Anything with type on it makes the mirror obvious; a symmetrical logo does not, so look for text or a corner mark before you send it to the press.

What the options do

The form above lists the options this tool is running today, straight from the server. This is what they are for.

Mirror
Left to right is the one used for iron-on transfers, screen printing, etching and anything printed onto the reverse of a transparent material — the image has to be backwards on the film so it reads correctly through the substrate. Top to bottom is much rarer: it is for the case where a sheet was fed into a scanner head-first when it should have gone in foot-first, and the result is a page whose lines run in the right order but whose glyphs are upside down. If what you actually have is a page turned a quarter or a half circle, rotate is the tool, not this one — a rotation keeps the words readable and a mirror does not.
Pages to flip
Which sheets get mirrored. The interesting case is a two-sided document scanned by holding it against the glass with the printed side away from you: every second page comes out mirrored, so ‘even’ or ‘odd’ puts the whole file right in one pass. You can also write 2-4,9 for a list, or 3- for everything from page three on. Pages you do not name are untouched, and the result counts how many of the flipped pages carried comments or form fields, because those do not mirror.

What this tool does not do

  • Comments, highlights, links and form fields are not mirrored. They sit beside the page’s drawing rather than inside it, so they stay exactly where they were — the result says how many pages that affected, and remove annotations will strip them if they are in the way.
  • A mirrored page is not an unreadable page. The letters are still stored as letters, so anyone can copy the text out of it and read it normally; this is a printing operation, not a way of obscuring anything.
  • It does not fix an upside-down scan. That is a 180° rotation, which keeps the words the right way round; mirroring makes them read backwards.
  • It mirrors the whole page, not one image or one block on it. There is no way to reverse a logo and leave the caption alone.
  • The mirror is taken about the page’s visible area — its crop box — so a page that has already been cropped mirrors within what you can see, not within the whole underlying sheet.

What happens to your file

The file is uploaded because Flip PDF pages runs on our server rather than in the browser tab. It is kept for at most 2 hours and the result you download for 24 hours, then a scheduled job deletes both — a job has to be able to read the file while it runs, and you have to be able to retry a failed conversion without re-uploading. Neither needs longer.

Nothing about the contents is logged, and no one reads your documents. The retention page lists the same numbers the code enforces, and the privacy policy says who can reach the storage they sit in.

Questions

What is the difference between flipping and rotating?
Rotating turns the page like turning a piece of paper on a desk: the words stay readable. Flipping reflects it, as a mirror does, so the words come out backwards. If your page is sideways or upside down you want rotate; if you need the image reversed for printing you want this.
I need a mirror image for iron-on transfer paper.
Left to right is the one. Print the flipped file onto the transfer sheet and the design reads correctly once it is pressed onto the fabric. Print a small test on ordinary paper first — a design with no text in it looks identical either way until it is on the shirt.
Why are my comments and links still the right way round?
Because they are not part of the page’s drawing. Annotations are separate objects positioned on top of it, and mirroring the drawing does not reach them. If they matter, strip them with remove annotations before you flip.
Does flipping reduce the quality or change the file size?
Neither, to any meaningful degree. Nothing inside the page is decoded or re-encoded — two short instructions are added around the existing content, so the images and fonts are the same bytes they were.
My scan came out mirrored on every second page.
That is a document held against the glass with the printed side facing away, and ‘odd’ or ‘even’ fixes it in one run. Look at which pages read backwards, and flip that half left to right.