The sideways photo problem
A photograph that looks upright on your phone and sideways on your computer is almost never actually rotated. Cameras and phones write the image in whatever orientation the sensor read it, then add an EXIF orientation tag — a small piece of metadata that says “display this turned 90 degrees clockwise”.
Software that honours the tag shows the photo correctly. Software that ignores it shows the raw pixels, sideways. Phones honour it. Modern browsers honour it. A great deal of desktop software, older photo viewers, print workflows and upload forms do not.
This tool rotates the actual pixels and writes the result upright, with no orientation tag to interpret. That fixes the file for every viewer rather than only the ones that read metadata — which is why a photo that already looks correct to you may still need rotating before you send it somewhere.
Why only right angles
Rotating by 90, 180 or 270 degrees moves every pixel to a new position without changing its value. Nothing is blended, nothing is interpolated, and the operation is exactly reversible — rotate right four times and you have your original pixels back.
Rotating by any other angle is a different operation. Pixels no longer land on the grid, so every output pixel has to be computed from several inputs, which softens the entire image. It also leaves empty triangles in the corners that must be cropped away or filled in. Both are legitimate things to want — straightening a crooked horizon, for instance — but they belong in a tool that shows you the crop, not behind a rotate button.
What the output format costs
The rotation is lossless; the saving may not be. If you save as JPEG, the rotated pixels are compressed again, and on a photo that was already a JPEG that is a second generation of loss. At quality 90 it is not visible, but it is real and it accumulates if you rotate the same file repeatedly.
Choosing PNG in the settings avoids that entirely: the output contains exactly the rotated pixels, at the cost of a much larger file. For a photograph headed to a phone or a form, JPEG at 90 is the sensible trade. For an image that will be edited further, PNG is the right answer.
Some desktop tools can rotate a JPEG losslessly by rearranging its compressed blocks rather than decoding them. That trick only works for right angles on images whose dimensions are multiples of the block size, and it is not available in the browser codecs used here — so this tool is honest about re-encoding rather than claiming a losslessness it cannot deliver.
Frequently asked questions
Does rotating an image reduce its quality?
The rotation itself does not — every pixel is moved, not blended, so the result contains exactly the same values in different positions. What can cost quality is saving: writing the result as JPEG re-compresses it, which on a photo that was already a JPEG is a second generation. Choose PNG in the settings if you need the output to be bit-for-bit faithful.
Why does my phone show the photo upright but my computer shows it sideways?
Because the photo is stored sideways with an EXIF orientation tag telling viewers to turn it. Phones and modern browsers honour the tag; a lot of desktop software ignores it. This tool applies the rotation to the actual pixels and writes the result upright, which fixes the file everywhere rather than only where the tag is read.
Can I rotate by an arbitrary angle, like 5 degrees?
Not here. Right-angle rotations move pixels without altering them; any other angle requires resampling, which softens the whole image and leaves empty corners that have to be cropped or filled. It is a genuinely different operation, and doing it badly is worse than not offering it.
What is the difference between mirror and flip?
Mirror reverses left and right, as a mirror does — the usual fix for a selfie that reads back to front. Flip reverses top and bottom, which is much rarer and mostly used for reflections. Both can be combined with rotation, and mirroring is applied before rotation so the buttons mean the same thing at any angle.
Can I rotate a whole folder at once?
Yes. Drop up to 100 images and the same rotation applies to all of them, each with its own progress and its own retry. Finished files download together as a ZIP. Because everything runs on your device there is no upload wait and no daily quota.