Some jobs need the page printed backwards. An iron-on transfer goes face down onto the T-shirt, so the design has to be printed as a mirror image or the text comes out reversed on the fabric. The same goes for a decal stuck on the inside of a window, a design printed on the back of clear film, and the text for a teleprompter, which is read off angled glass.
Then there's the opposite problem: a scan or export that came out mirrored and needs flipping back.
Flip pages mirrors PDF pages left to right or top to bottom, in your browser, without turning them into images.
Flipping and rotating are different things
It's tempting to think a mirrored page is just a rotated one. It isn't, and no amount of rotating will fix it.
Rotating turns the page around its centre. The text is still readable, just at an angle or upside down. Mirroring reflects the page across a line, so the letters themselves come out backwards. A rotated "R" is still an R. A mirrored one isn't.
There are two mirrors:
- "Horizontal" reflects the page left to right, across a vertical line down the middle. Text reads backwards, like in a mirror. This is the one for transfers and decals.
- "Vertical" reflects top to bottom, like a reflection in water. The page ends up upside down, with the letters mirrored too.
Flip a page both ways, horizontal and then vertical, and you get the same result as rotating it 180 degrees. So if your page is simply upside down, you don't need this tool. Use Rotate PDF instead (the guide on rotating PDF pages explains why a rotation sometimes doesn't stick).
How the flip is done
A PDF page is a list of drawing instructions: put this text here, draw this line there, place this image at this spot. Flip pages doesn't touch any of them. It adds one instruction in front that says, in effect, "draw everything that follows reflected across the middle of the page".
That has two useful consequences. Nothing is converted to a picture, so text and vector graphics stay as sharp as the original at any size, and the file size barely changes. And because the original instructions are untouched, flipping the same pages again with the same setting brings them straight back to normal.
The page's own settings come through as well. Bookmarks, form fields, rotation and crop settings are kept. Links and comments are moved to their mirrored position so they still sit over the right part of the page.
Flipping pages step by step
- Open Flip pages and add your PDF. A preview of the first page appears.
- Next to "Flip", choose "Horizontal" or "Vertical". The preview updates straight away.
- Leave "Pages" empty to flip every page, or type a selection such as "1-3" or "even".
- Click "Flip pages" and download the result. It's saved as flipped-yourfile.pdf.
The preview only shows the first page. If you're flipping a selection, open the downloaded file and check that the right pages changed, since a typo in the page list is easy to miss.
"Horizontal" is selected by default, which is what most people want. Vertical flips are rarer: printing on the underside of something that's viewed from below, or fixing a scan that was mirrored top to bottom.
Printing a mirrored transfer
A few practical things that catch people out:
- Some printer drivers have their own mirror setting, often called "Mirror image" or a T-shirt transfer mode. If you flip the PDF and also turn that on, the two cancel out and the print comes out the right way round. Use one or the other.
- Print a test on plain paper first. Hold it up to a window with the printed side facing the glass. Seen from the other side, the text should read normally.
- Check the page size. Transfer paper usually comes in the same sizes as normal paper, but if your design isn't on the right size page, fix that in Resize PDF before you print, not after.
- Print at "Actual size" rather than a fit option if the design has to come out at an exact size.
What doesn't get mirrored
There's a catch with keeping comments and form fields. They're moved, but they aren't drawn backwards. A comment or a filled-in form field is a separate object sitting on top of the page, with its own small drawing of how it should look. Flip pages moves that object to the mirrored spot, and the object itself still reads the normal way.
On screen that's usually what you want. For a transfer, it isn't. If your design has typed text in form fields, or stamps and text boxes added as comments, those would print readable on the transfer paper and come out backwards on the shirt.
The fix is to flatten first. Flatten PDF with "Flatten form fields and annotations" draws all of those into the page content, and then Flip pages mirrors them along with everything else. The guide on flattening a PDF covers the modes.
Flip pages also works only in those two directions. It doesn't do arbitrary angles, and it won't straighten a scan that's slightly tilted. That's a job for Deskew PDF.
Keep both versions
Once it's flipped, a transfer file is useless for anything else: you can't proofread it, and it looks wrong to everyone you send it to. Keep the original as your working copy, make edits there, and flip a fresh copy each time you print. The download is named flipped-yourfile.pdf, which helps, but it's worth renaming it to something like "shirt-design-MIRRORED.pdf" so nobody prints the wrong one by accident.
Also useful: Rotate PDF · Flatten PDF
