Rotate Image

Why photos end up sideways in the first place

A phone's camera sensor has one fixed orientation. When you hold the phone upright, the camera does not rotate the pixels — it saves them as captured and writes a small number into the file's EXIF metadata saying "display this turned 90° clockwise". There are eight possible values of this orientation tag, covering the four rotations and their mirror images.

Most modern software reads the tag and shows the photo the right way up, which is why it looks fine in your gallery. Trouble starts when something along the way ignores the tag or throws it away: older Windows viewers, some content-management systems, forms that strip metadata for privacy, and a good number of upload pipelines. The pixels underneath were always sideways; the tag was the only thing keeping them upright.

This tool reads the orientation tag when it opens a file, so the preview matches what your gallery shows, and then bakes the rotation you choose into the pixels themselves. The saved file has no orientation tag at all — it is simply the right way up, in every program, with no metadata needed.

Quarter turns are lossless; other angles are not

Rotating by 90°, 180° or 270° is a reshuffle. Every pixel moves to a new position and keeps its exact value, and the width and height swap for 90° and 270°. Nothing is invented and nothing is blurred. The page builds this transform from exact zeros and ones rather than from sine and cosine — the cosine of 90° in floating point is 0.00000000000000006, not 0, and a transform built from that is a hair off axis, which some browsers respond to by resampling every pixel.

Any other angle is a different operation. The rotated pixel grid no longer lines up with the output grid, so each new pixel has to be interpolated from its neighbours. Done well, as here, the result is very slightly softer than the original — invisible at normal viewing sizes, but it is why rotating the same photo by 1° ten times in a row is a bad idea. Rotate once, from the original, by the total amount.

Saving re-encodes the image. For a PNG that is lossless. For a JPEG it is a fresh round of compression, so the default quality of 92 is deliberately high; a JPEG re-saved at 92 is visually indistinguishable from the original for nearly all photographs. If you need a byte-perfect copy of a JPEG with only the orientation changed, that requires a lossless JPEG transform tool working on the compressed blocks, which a browser canvas cannot do.

Expand, keep the size, or crop to fill

Turning a rectangle by an angle that is not a right angle makes its corners stick out of the original frame and leaves four triangles of empty space. There are three sensible things to do about that, and the right one depends on the job.

Expand canvas keeps every pixel of the photo and grows the canvas to fit the rotated shape. The empty triangles become transparent (in PNG or WebP) or the colour you pick. This is what you want for a cut-out product shot, a logo, or a diagram you will place on another background.

Keep the original size holds the canvas at the photo's own dimensions, so the corners of the image are trimmed and small empty wedges appear at the edges. It suits a template with a fixed size, where the slot must not change shape.

Crop to fill finds the largest rectangle that lies entirely inside the rotated photo, so there are no empty corners at all. It is the straightening option: a horizon tilted by 2° on a 6000 × 4000 photo crops to 5871 × 3797, keeping about 93% of the area. At 5° you keep about 84%, and at 10° about 71% — which is why straightening is best done with the smallest correction that looks level.

Straightening a crooked photo

Find a line in the picture that should be horizontal or vertical — a horizon, the edge of a table, a door frame, the side of a building — and adjust the angle slider until it lines up with the edge of the preview. Most handheld tilt is between half a degree and three degrees, and the slider moves in half-degree steps; type an exact value such as 1.3 into the angle box when you need finer control.

Positive angles turn clockwise. If the right side of the horizon is lower than the left, the picture needs turning anticlockwise, which is a negative angle.

Vertical lines in architecture are a separate problem. Tall buildings photographed from the ground lean inwards because of perspective, not because the camera was rotated, and no amount of rotation fixes that — it needs a perspective (keystone) correction, which this tool does not do.

Batches, formats and what happens to metadata

Drop as many images as you like. Each one keeps its own rotation, so a mixed batch of portrait and landscape phone photos can be fixed one by one; when they all need the same treatment, set it on one and press Use these settings for all. The batch is processed one image at a time with a progress bar, so a large set never freezes the page, and the results come back as individual downloads plus a single ZIP.

Same format as the original keeps JPEG as JPEG and WebP as WebP; formats a browser cannot write, such as GIF or BMP, come out as PNG. If you ask for WebP in a browser that cannot encode it — Safari is the common case — the file is saved as PNG and named .png, and the page tells you, rather than producing a PNG with a .webp extension.

Re-encoding drops the EXIF block, which removes the camera model, date taken and any GPS coordinates along with the orientation tag. That is usually a privacy bonus. If you need to keep the date or location, keep the original file as well.