Why rotate or flip an image?
Image rotation is one of the most common photo editing operations. Whether you took a photo in portrait mode when you wanted landscape, or your scanner produced an upside-down document, rotating the image is the first correction to make. Digital cameras record a metadata tag called EXIF Orientation that indicates how the photo was taken, but not all software reads it correctly, resulting in images displayed sideways or upside down.
Types of rotation
Several geometric transformations can be applied to images:
- 90° rotation (quarter turn): rotates the image one quarter turn clockwise or counterclockwise. Width and height are swapped. For example, a 4000×3000 px photo becomes 3000×4000 px.
- 180° rotation (half turn): turns the image upside down. Dimensions remain the same. Useful for scanned documents that are inverted.
- Free rotation (arbitrary angle): rotates the image by any angle between -180° and +180°. The output canvas expands to contain the entire tilted image.
- Horizontal flip (mirror): reverses the image from left to right, like a mirror reflection. Essential for correcting selfies inverted by front-facing cameras.
- Vertical flip: reverses the image from top to bottom. Used in creative photography for water reflection effects.
Common use cases
| Situation | Transformation | Result |
|---|
| Photo taken in portrait | 90° left or right rotation | Correctly oriented image |
| Upside-down scanned document | 180° rotation | Readable document |
| Mirrored selfie | Horizontal flip | Readable text, natural face |
| Slightly tilted horizon | Free rotation (-5° to +5°) | Straightened photo |
| Social media photo | Rotation + cropping | Improved composition |
EXIF Orientation: the hidden problem
When you take a photo with a smartphone, the sensor always captures the image in the same physical orientation. It is the EXIF Orientation tag (values 1 to 8) that tells software how to display the image. The most common values are:
- 1: normal orientation (no rotation)
- 3: 180° rotation
- 6: 90° clockwise rotation
- 8: 90° counterclockwise rotation
Some platforms (older browser versions, email clients) ignore this tag, displaying the photo rotated. Our tool applies an actual pixel rotation that works everywhere regardless of EXIF data.
The mathematics of rotation
Rotating a point (x, y) around the origin by angle θ produces new coordinates:
- x' = x × cos(θ) − y × sin(θ)
- y' = x × sin(θ) + y × cos(θ)
For an image of width W and height H rotated by θ, the resulting canvas dimensions are: W' = W·|cosθ| + H·|sinθ| and H' = W·|sinθ| + H·|cosθ|. For θ = 90°, this gives exactly W' = H and H' = W.
Privacy and security
Our rotation tool works entirely in your browser using the HTML5 Canvas API. Your images never leave your device — no data is sent to any server. Process up to 10 images simultaneously and download them individually or as a ZIP archive.
Frequently Asked Questions
How do I rotate an image 90 degrees online?
Drag and drop your image into our tool, then click the 90° right or 90° left button. The preview updates instantly. Then click Apply & download to save the rotated image.
How do I flip an image horizontally?
Use the Flip horizontal button to mirror the image from left to right, or Flip vertical to mirror it top to bottom. Perfect for correcting mirrored selfies.
Does rotation change the image dimensions?
A 90° or 270° rotation swaps width and height. A 180° rotation or flip keeps the original dimensions. Free-angle rotation expands the canvas to fit the tilted image.
Are my images uploaded to a server?
No, all processing happens in your browser via the HTML5 Canvas API. Your images stay on your device and no data is transmitted.
Can I rotate multiple images at once?
Yes, you can load up to 10 images. Select each image to apply a different rotation, then download all as a ZIP file.
What image formats are supported?
All common image formats are accepted: JPEG, PNG, WebP, GIF, BMP, SVG. Export is done as JPEG (92% quality) or PNG (lossless) depending on the original format.