1Upload the BMP images that came out the wrong way round.
2Pick a turn of 90, 180 or 270 degrees.
3Apply the rotation; the pixels and the orientation flag are reconciled so every viewer agrees on which way is up.
4Download the rotated BMP file.
Rotate BMP FAQ
Does the format decide whether rotation is lossless?
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It does. BMP is essentially raw uncompressed RGB rows with a small header, so it is perfectly lossless and enormous — often 10-20x the size of the same image as PNG. That property is exactly what determines whether a quarter turn is free or costs a re-encode.
Anything specific to BMP I should know?
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Yes — because nothing is compressed, a BMP is fast to read and edit but punishing to upload, and it carries no metadata to preserve. It is the kind of thing that explains why a file looks right in one application and wrong in another.
How does Rotate BMP turn the file?
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Concretely, the pixel array is transposed and written back exactly, so a rotation of a lossless image is free in fidelity terms at any right angle and costs only resampling at an arbitrary one. Quarter turns and half turns are the common case and take the cheapest path available for the format.
Does the alpha channel survive?
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Yes. PNG and TIFF carry a full 8-bit alpha channel and it is preserved end to end. It is only flattened if you deliberately target a format that has no alpha, in which case transparent pixels are composited onto white.
Is there a file size limit on Rotate BMP?
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Yes: free accounts process images up to 5 MB each; lossless sources hit that ceiling sooner than photographs do, because nothing has been thrown away yet. If you are over it, converting to PNG first is often enough on its own — a BMP is routinely ten to twenty times the size of the identical image as PNG.
Why would a modern-format site run Rotate BMP?
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WEBP.to is built around the modern replacement for both of the old defaults: one format that does lossy, lossless, alpha and animation, and reliably lands smaller than the JPEG or PNG it came from. People arrive here having decided the old defaults are costing them bandwidth, and that decision immediately raises the rest: what size, what quality, what happens to the transparency. Rotate BMP is on the same upload and the same account so those questions get answered in one place.
Once Rotate BMP has run, what is worth doing next?
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The converter on this site moves images to and from WebP, PNG, JPG and AVIF, which is where you decide whether a smaller file is worth losing the older browsers. Doing it in that order matters: pick the pixels first and the container afterwards, because the container is the cheap decision and the pixels are the expensive one.
Do the sibling sites run something different?
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The engines are identical — same libraries, same workers, same caps. What is different is the opinion attached, and the opinion here rests on a property of the format this site is named after: the same .webp extension can hold a lossy VP8 frame, a lossless one, or an animation, so the sensible processing path is decided per file rather than per extension.
What happens to my file, and is an account required?
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No account is needed. Uploads and results are kept for about 24 hours, which leaves time to download the result, and are then deleted automatically; nobody reads, lists or indexes them. Several files in one job need a paid plan.
