Flip PDF

Heat-transfer paper for T-shirts, sublimation prints for mugs, window decals read from outside, and designs printed on the reverse of clear film all need a mirror image, so that the design reads correctly once it is flipped onto the final surface. Many printer drivers hide the "mirror" option or lack it entirely. Flip the PDF horizontally here, print at actual size, and the result is the right way round on the finished piece.

Overhead document cameras, webcams used for remote teaching and some phone scanner apps produce mirrored pages, where every word reads backwards. A horizontal flip restores normal reading. If the page is also upside down, apply a vertical flip as well or turn it with Rotate PDF. Because only the selected pages are changed, you can fix the odd reversed page in a long scan without touching the rest.

Many online tools flip a PDF by turning every page into a picture, mirroring the picture and putting it back — which blurs text, makes it unsearchable and often makes the file much bigger. PDFDoco instead adds a mirroring instruction to each page, the same mechanism PDF viewers use for zoom and rotation. Nothing is re-encoded: images keep their original data, text stays text, and the file size barely changes.

A horizontal flip mirrors across the vertical center line: the left margin becomes the right margin and text reads backwards. A vertical flip mirrors across the horizontal center line: the page is upside down and reversed. Flipping both ways is the same as rotating 180°, so if all you need is to turn a page the right way up, rotating is the better choice because the text stays readable.