Rotate BMP bitmap images online for free. Fix the orientation of Windows graphics and legacy images in 90° turns or by a fine angle.
BMP (the Windows Bitmap format introduced by Microsoft in the late 1980s) stores raw pixel data with an optional simple header and color table. Unlike JPEG, BMP has no EXIF orientation tag — there is no metadata flag a viewer can flip to display the image upright. The only way to actually re-orient a BMP is to rewrite the pixel grid, which is exactly what this tool does.
Print Screen historically wrote 24-bit BMP; older industrial HMIs and embedded controllers still do. Rotating in place keeps the format identical so the original viewer or PLC software still loads it.| Property | BMP | PNG | JPEG |
|---|---|---|---|
| Compression | None by default; 4/8-bit RLE optional | Lossless DEFLATE | Lossy DCT |
| Typical size (1920x1080, 24-bit) | ~6.3 MB | ~1-2 MB | ~200-500 KB |
| Color depth | 1, 4, 8, 16, 24, 32 bpp (the editor writes 24-bit) | 1-16 bpp gray, up to 64-bit RGBA (the editor writes 8-bit) | 8-bit per channel, 24-bit color |
| Transparency | Format allows 32-bit alpha; the editor's BMP output is flattened onto white | Yes (alpha channel) | No |
| EXIF orientation tag | No — physical rotation required | No — physical rotation required | Yes — the editor makes the pixels upright and resets it to 1 |
| 90/180/270 rotation | Pixel-perfect, lossless | Pixel-perfect, lossless | Re-encoded as a new JPG at the "Quality" you set (85 by default) |
| Best for | Legacy Windows, GDI apps, raw pipelines | Web, screenshots, UI, transparency | Photos, web sharing, smaller files |
| Angle | What it does | Quality | When to use |
|---|---|---|---|
| 90 clockwise | Quarter turn right | Pixel-perfect (lossless) | Portrait scan came in landscape, right-side-up needed |
| 90 counter-clockwise | Quarter turn left | Pixel-perfect (lossless) | Same as above but rotated the other way |
| 180 | Upside down | Pixel-perfect (lossless) | Scanner fed face-down, camera held upside-down |
| Custom (1-89, 91-179, etc.) | Arbitrary angle | Resampled, minimal loss | Crooked scan, tilted handheld capture, design effects |
Right-angle rotations (90, 180, 270) only swap or reverse rows and columns of the pixel grid — every original pixel value is preserved. Custom angles need bilinear or bicubic resampling because the rotated grid no longer aligns with the original pixel centers.
No, not for 90, 180, or 270 rotations. BMP stores raw pixel data, so a quarter or half turn just rewrites the pixel array in a different order — every byte of color information is preserved exactly. Only custom angles (anything that's not a multiple of 90) require resampling, and even then the loss is minimal because BMP itself doesn't add lossy compression on top.
Because BMP is uncompressed by default. A 1920x1080 24-bit BMP is roughly 6.3 MB whether you rotate it or not — the byte count comes from width x height x bytes-per-pixel plus a small header. To shrink the output, pick PNG with "Save as" (lossless and much smaller than BMP) or use Compress BMP. If size matters more than the format, BMP to PNG gives lossless output at roughly 20-30% of the BMP size, and BMP to JPG gets it well under 1 MB at typical quality settings.
Phone photos are JPEGs, and JPEG includes an EXIF Orientation tag (1-8) that viewers read to display the image upright without rewriting pixels. The BMP file format has no orientation metadata at all — the pixel grid is the only source of truth for which way is up. So rotating a BMP always means physically rewriting the pixel data, which is exactly what this tool does.
Not in a BMP. Modern BMP files using BITMAPV4HEADER or BITMAPV5HEADER (Windows 95 and later) can carry a per-pixel alpha channel, but the BMP the editor writes is 24-bit, so transparency is flattened onto white and the editor says so before you download. Save as PNG, WebP or TIFF to keep it; with "Transparent" chosen under "Background for exposed corners", fine-angle corners stay transparent in those formats too.
Yes — drop up to 50 BMP files at once (a mixed batch works too). The rotation angle you set applies to every file in the batch; "Download all (.zip)" saves every rotated result in one ZIP, or use "Download one by one" to save them separately.
The tool processes files in your browser, so the practical limit is how much memory your browser tab can hold. A 24-bit BMP is fully decoded as a raw pixel buffer (about 4 bytes per pixel including padding), so an 8000x6000 image needs roughly 200 MB of working memory in your browser tab. For typical scanner and screenshot output up to 4K, processing is fast, and nothing is uploaded. The saved image can be at most 16,384 px per side and 120 megapixels.
Keep BMP only if your downstream tool requires it — older Windows GDI applications, some industrial or medical software, certain game-asset pipelines, and a handful of embedded systems. For everything else, rotating then converting via BMP to PNG (lossless, smaller) or BMP to JPG (much smaller, lossy) is more practical. You can also do the reverse trip with PNG to BMP if you need to feed a legacy app.
The output uses a standard BITMAPINFOHEADER (40-byte) container, which is the universally compatible Windows BMP header and is read by every Windows version since Windows 3.0. Files using the older 12-byte BITMAPCOREHEADER (OS/2 1.x style) are upgraded to BITMAPINFOHEADER on save. The output is always 24-bit, so a 32-bit alpha channel from a V4/V5 input is flattened onto white; save as PNG to keep it.
You can resize in the same session — open Resize and set a "Width", "Height" or "Size preset" — and pick another format with "Save as". The editor has no colour-palette, bit-depth or DPI setting. For pure size shrinking after rotation, see also Compress BMP.