Rotate and flip your images

Why a photo shows up sideways

Phones and cameras store an orientation flag in the file instead of rotating the pixels. Some apps honor it and others ignore it, so the picture appears on its side. This tool rewrites the pixels and saves a truly upright image that looks the same everywhere.

Turns of 90, 180 and 270 degrees are lossless for pixels: each point just moves. A free angle forces the image to be resampled, which softens it very slightly.

Image size after rotating

\[ \text{new width} = \text{width} \times \left| \cos \theta \right| + \text{height} \times \left| \sin \theta \right| \]

\[ \text{new height} = \text{width} \times \left| \sin \theta \right| + \text{height} \times \left| \cos \theta \right| \]

At 90 and 270 degrees, width and height swap. At 180 they stay the same.

Flip, PNG or JPG: what to pick

• Flip horizontal swaps left and right, handy for a selfie or reversed text.
• Flip vertical turns the picture upside down along its middle.
• PNG keeps transparency; JPG is smaller for photos but fills empty corners with a color.
• An animated GIF becomes a still picture: only the first frame is kept.

Rotate an image: the most common cases

When you rotate an image, it is almost always for one of these reasons. So the right setting depends on the problem.

• Sideways photo: make a quarter turn to stand it up.
• Upside-down scan: turn it 180 degrees.
• Reversed selfie: apply the horizontal flip to restore the real text direction.
• Tilted horizon: set a small angle, such as 2 degrees, to level the line.

Also, you can rotate several images at once. For example, you fix a whole set of vacation photos in one pass.

Why does a photo end up sideways? Because the phone writes the shooting direction into the file. Then some apps read that note, but others ignore it. As a result, the same photo looks upright here and sideways there. So to rotate an image for good, save a rewritten copy.

How to rotate an image in 4 steps

1. First, drop one or more images.
2. Next, pick the quarter turn, the flip or the free angle.
3. Then watch the preview, which updates live.
4. Finally, download each image or a single ZIP.

If you dislike the result, start again from the original. Then choose another setting. Since turns of 90 degrees lose no pixels, you can chain several quarter turns without hurting quality. In practice, a document photographed at an angle needs a quarter turn, then sometimes a small angle. So work in that order. That way, you can rotate an image in two moves.

Mistakes people make when they rotate an image

Then, to remove empty corners, open crop image. To change the size, go through resize image. To adjust the colors, use the photo editor.

Picking the right way to rotate an image

• For a quarter turn, use the buttons, because the result is perfect.
• For a tilted horizon, use the slider in small steps.
• On the other hand, avoid several free angles in a row, since each resampling softens the image a little.
• When you need a lighter file, finish with compress image.
• If you change format, go through convert PNG to JPG.

In short, one well-chosen angle beats three small tries. So measure the tilt before you move the slider.

Finally, think about the end use. For a website, a PNG or a JPG works fine. For printing, keep the biggest size you can. If you want to rotate an image for social media, check the size the network expects. Likewise, reread the preview before you download.