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ARW vs BMP

ARW vs BMP

A detailed comparison of Sony RAW ARW and BMP Image — file size, quality, compatibility, and which format to choose for your workflow.

Convert ARW → BMP
ARW

Sony RAW ARW

Raster & Vector Images

ARW is Sony Alpha RAW format for professional and mirrorless cameras.

About ARW files
BMP

BMP Image

Raster & Vector Images

BMP is an uncompressed raster image format native to Windows. Files are large but preserve exact pixel data with no compression artifacts. Rarely used on the web due to file size.

About BMP files

Strengths Comparison

ARW Strengths

  • Full 14-bit sensor data on flagship bodies.
  • Rich Sony metadata (Creative Style, DRO, Focus Magnifier).
  • Supported by every major raw processor.
  • Lossless compression available on modern bodies.

BMP Strengths

  • Dead-simple format — trivially easy to read and write.
  • Lossless and uncompressed — perfect bit-exact pixel storage.
  • Universally supported in Windows applications since 1985.
  • Supports 1, 4, 8, 16, 24, and 32-bit color depths.

Limitations

ARW Limitations

  • Proprietary — new Sony body launch = Lightroom update required.
  • Lossy compression was the only option on many older bodies (visible banding in highlights).
  • File sizes are huge on 50+ MP bodies.
  • Some ARW variants use 16-bit layout that breaks older third-party tools.

BMP Limitations

  • Enormous file sizes — no meaningful compression in typical use.
  • Not a web format — browsers support it but nobody serves BMPs over HTTP.
  • No metadata support (no EXIF, no ICC profile in practice).
  • Multiple header versions mean "a BMP" is ambiguous — parsers must handle several variants.

Technical Specifications

Specification ARW BMP
MIME type image/x-sony-arw image/bmp
Extension .arw —
Container TIFF/EP with Sony MakerNote tags —
Bit depth 14-bit (flagship); 12-bit (entry) —
Compression Uncompressed, Lossless, Lossy None (typical); RLE 4/8 bit (rare)
Extensions — .bmp, .dib
Color depths — 1, 4, 8, 16, 24, 32 bits per pixel
Byte order — Little-endian

Typical File Sizes

ARW

  • 24 MP ARW (A7 III, A7C) 25-45 MB
  • 42 MP ARW (A7R III) 50-90 MB
  • 61 MP ARW (A7R IV, A7R V) 75-130 MB

BMP

  • Small icon (32×32) 4 KB
  • Screenshot (1920×1080) ~6 MB
  • 4K image (3840×2160) ~25 MB
  • Scanned A4 at 300 dpi ~25 MB

Ready to convert?

Convert between ARW and BMP online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.

Convert ARW to BMP

Frequently Asked Questions

ARW (Sony RAW ARW) is an image format used to store raster graphics — a two-dimensional grid of pixels describing a picture. It is part of the raster & vector images family and designed around a specific trade-off between file size, visual fidelity, and feature support (transparency, colour depth, compression type). Photographers, web designers, and content creators choose ARW when its particular strengths match the publishing target.

BMP (Bitmap) is a raster image format developed by Microsoft for Windows. It stores images with no compression by default, resulting in large file sizes but pixel-perfect quality. It has been part of Windows since version 1.0.

Most desktop photo viewers (Windows Photos, macOS Preview, GIMP, Photoshop, Affinity Photo) open ARW natively. On mobile, iOS Photos and Google Photos display ARW in the gallery when supported by the OS. If the format is rare or new, convert to JPG or PNG first — both are universally readable — using our ARW to JPG or ARW to PNG converter.

BMP files open in Windows Paint, Photos, macOS Preview, GIMP, Photoshop, and virtually any image viewer. All Windows applications support BMP natively.

Upload the ARW to KaijuConverter and pick a target format (JPG, PNG, WebP, HEIC, TIFF, BMP, SVG, PDF). The conversion runs in the browser via ImageMagick and returns a download in seconds. No account or installation required; both input and output delete automatically within two hours.

It depends on the task. JPG is the smallest file size for photographs; PNG is lossless with transparency; ARW has its own niche that may favour colour depth, animation, or encoding efficiency over one or both of those. For the final web publish, test all three and measure file size plus visible quality on real content.