The usual reason to need this is a photo that looks correct on your phone and sideways everywhere else. That is not a fault in the image — it is a disagreement about metadata, and understanding it explains why rotating properly matters.
The EXIF orientation problem
Phone cameras do not rotate the image when you turn the phone. They save the pixels exactly as the sensor read them and add a small metadata note saying which way up it should be displayed. Photo apps and modern browsers read that note and rotate on the fly. Plenty of other software — older desktop programs, some upload processors, certain printing services — ignores it entirely and shows you the raw sideways pixels.
This tool settles the argument. It decodes the image with the orientation flag applied, rotates the actual pixels, and writes out a file that is genuinely the right way up. No metadata note is involved in the result, so nothing downstream can disagree about it.
Why only right angles
Rotating by 90, 180 or 270 degrees moves every pixel to a new position on the grid without needing to invent any new ones. The result is mathematically identical to the original, just arranged differently — nothing softens, nothing blurs, no quality is lost at all.
Rotating by an arbitrary angle is a different operation entirely. Every pixel lands between grid positions, so each one has to be interpolated from its neighbours, which softens the whole image. It also leaves empty triangles at the corners that must be filled or cropped away. That is a straightening tool rather than a rotation tool, and it belongs on its own page with its own controls.
- 90° clockwise — for a photo lying on its left side.
- 90° anticlockwise — for a photo lying on its right side.
- 180° — for a photo that is completely upside down, common with scanned pages fed in the wrong way.
Dimensions swap on a quarter turn
A 4000×3000 landscape rotated by 90° becomes a 3000×4000 portrait. That is unavoidable and correct, but worth knowing if something downstream expects specific dimensions — rotate first, then resize, not the other way round.
The output is PNG, so the rotation costs nothing in quality even if the source was a JPEG. Rotating a JPEG and re-saving it as a JPEG would re-compress the whole image for no reason. If you need a JPG at the end, compress afterwards. Everything runs in this tab with nothing uploaded.