Does flipping a BMP lose any quality?

No. Flipping is a pure pixel rearrangement — every pixel is preserved at its full original bit depth. Microsoft's own IWICBitmapFlipRotator describes the operation as a coordinate transform along an axis, with no resampling involved. Compression and quality settings only matter if you choose to recompress the output.

Why does my BMP open upside-down in some viewers but right-side-up in others?

BMP scanlines are stored bottom-up by default; the format also allows top-down ordering by writing a negative biHeight in the header. Tools that ignore the sign assume bottom-up and render top-down BMPs inverted. Apply a vertical flip and re-save to normalise the orientation.

Should I flip horizontally or vertically for an iron-on transfer?

Horizontally. Heat-transfer paper, sublimation transfers, and most screen-printing positives need a left-to-right mirror so the design reads correctly once the paper is flipped onto fabric. Vertical flip is for upside-down captures, not transfers.

Will the output also be a BMP, or do I have to keep the format?

Output stays as .bmp here. If you'd rather move to a smaller modern format after flipping, run BMP to PNG for lossless or BMP to JPG for photographic content — typical 24-bit 1080p shrinks from ~6 MB to ~1–3 MB (PNG) or ~200–500 KB (JPG).

Can I flip a 1-bit (black-and-white) or indexed BMP without breaking the palette?

Yes. The flip operation works on the pixel grid; it doesn't touch the colour table or palette indices. A 1-bit fax-style BMP, an 8-bit indexed sprite sheet, or a 256-colour Windows icon all flip cleanly and remain in the same bit depth unless you change it under Image bit depth.

Does this also work for .dib files or BMPs without the .bmp extension?

Files genuinely in the BMP/DIB container will work if you rename them to .bmp first. The container is detected by the BM magic bytes at offset 0, not by the extension. Truly legacy .dib device-independent bitmaps with the older BITMAPCOREHEADER are also accepted.

Can I flip and crop or rotate in the same step?

Not in this single tool, but the workflow is fast: flip here, then run Crop BMP or Rotate BMP on the result. Each step is lossless on a pure BMP, so chaining them doesn't degrade the image.

Why is my flipped 32-bit BMP showing a black instead of a transparent background?

32-bit BMPs technically support an alpha channel via BI_BITFIELDS, but many legacy Windows viewers ignore it and render the alpha as opaque black. The flip itself preserves the alpha bytes — the issue is the viewer. Re-save as BMP to PNG if you need reliable transparency across modern apps.

Can I flip multiple BMP files in batch?

Yes. Drop several .bmp files into the upload area and the same flip direction and compression settings apply to all of them. Output is delivered as individual files, ready to download.

Flip BMP

Flip BMP bitmap images online for free. Mirror horizontally or vertically with optional compression.

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