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BMP to AVIF converter

Convert BMP images to AVIF format

No watermarkFree & unlimited
All processing happens in your browser. No data is sent to any server.

Bitmap to AVIF is the widest compression gap in the whole image matrix: an entirely uncompressed format on one side and the still-image profile of the AV1 video codec on the other. When it works, a six-megabyte bitmap becomes something in the low hundreds of kilobytes with no visible difference. The caveat is that encoding is done by your browser rather than a bundled codec, and support for writing AVIF from a canvas lags well behind support for reading it. Check that on your own machine first.

Key facts about BMP to AVIF converter

Key facts about BMP to AVIF converter
EncoderYour browser's own AVIF encoder, reached through canvas.toBlob with the image/avif MIME type. No AV1 library is downloaded by this page.
Encoder availabilityThe real limit. With no AVIF writer, the HTML specification has the canvas fall back to PNG data, so a file named .avif can hold PNG bytes.
Typical size deltaWith a working encoder, a 1920x1080 bitmap of 6,220,854 bytes commonly lands between 80 KB and 250 KB at quality 90, about half what WebP gives.
Quality controlA slider from 30 to 100 in steps of 5, default 90. AVIF holds up far better at low settings than JPG, so 50 is often still acceptable.
Encoding speedThe slowest target in this matrix: a large bitmap can take several seconds per file where WebP takes a fraction of one.
TransparencyAVIF stores an alpha plane, so a bitmap that decoded with alpha keeps it. Standard 24-bit bitmaps have none and the result is opaque.
Colour depthEight bits per channel through the canvas, so the 10 and 12-bit AVIF modes are unreachable here.
Opens the resultChrome 85 and later, Firefox 93 and later, Safari 16 and later, Windows 11 with the AV1 extension, macOS Ventura onward. Older Windows and most desktop editors will not.

What happens to your file

Nothing about this page talks to a server. The bitmap is read through an object URL, decoded by the BMP reader built into your browser, and painted onto a canvas belonging to this tab. The output request goes to canvas.toBlob, a browser API, so the AV1 encoding happens inside the browser process on your own CPU rather than in a cloud transcoder. With no upload there is no queue, no job id and no temporary file on a remote disk.

About this tool

  1. 1

    Select the bitmaps

    Drop one or more .bmp files, up to twenty at a time and 500 MB apiece.

  2. 2

    Pick a quality

    Start at the default 90. AVIF tolerates aggressive settings well, so try 60 on photographic bitmaps and compare.

  3. 3

    Resize oversized sources

    The presets run before the encode, which also cuts encoding time sharply on large scans.

  4. 4

    Convert, then verify the size

    Expect this to take longer than other targets. Check that the result is far smaller than the bitmap; a PNG-sized file means your browser fell back.

Specs & compatibility
Input and outputTakes .bmp only (image/bmp) and returns .avif with the image/avif type; any other extension is refused before decoding.
Conversion pathBMP to AVIF runs in three steps: an <img> element decodes the bitmap, 24-bit and 32-bit variants alike; the pixels land on a 2D canvas in this tab; then canvas.toBlob with the image/avif type returns the finished file.
Browser supportThe bitmap side decodes in every current browser, while writing the AVIF needs a Chromium browser, since Firefox and Safari return PNG bytes under the .avif name.
Controls for this pairA 30 to 100 quality slider (steps of five, default 90) drives the AVIF encode, max-dimension presets from 3840 down to 200 px resize the BMP first, and the strip-metadata toggle is moot on this pair.
Batch, caps and namingTwenty BMP files per run at 500 MB each; one result downloads as a single AVIF, several as converted-avif-files.zip, zipped by JSZip 3.10 in page memory.
Device ceilingThe canvas caps it: past roughly 16,384 px a side Chromium refuses the bitmap and iPhone Safari gives up sooner, so an oversized BMP fails before any AVIF bytes exist.
  • Test one small bitmap first to confirm your browser actually writes AVIF, rather than converting a folder into mislabelled PNGs.
  • Serve AVIF behind a picture element with a WebP or JPG fallback, since a meaningful share of visitors still cannot decode it.
  • For pure interface screenshots the gain over WebP narrows, so the extra encode time may not pay.
  • If a 4K bitmap stalls the tab, apply the Full HD preset first; AV1 cost scales with pixel count, not file size.
  • AV1 still-image output via the browser encoder
  • Quality range 30 to 100, default 90
  • Pre-encode resizing to cut AV1 cost
  • Twenty bitmaps per run with a local ZIP
  • Modernising uncompressed bitmap product shots for a site that already serves AVIF.
  • Getting scanner output under an email attachment limit.
  • Benchmarking AVIF against WebP on your own source material.
Compare file sizes. A genuine AVIF of a photographic bitmap is a small fraction of the source, typically under 300 KB at full HD. A megabyte-plus file that looks pixel-perfect is almost certainly PNG data under an .avif name; a hex viewer settles it.
AV1 intra coding searches far more prediction modes and block partitions than VP8 does, and that search is exactly why AVIF compresses better. On a full HD bitmap the difference is often an order of magnitude. Resizing before encoding is the most effective remedy.
For photographic content, generally yes: at matched quality AVIF files are commonly 30 to 50 percent smaller and degrade more gracefully. For flat interface bitmaps the gap narrows sharply and lossless PNG can beat both. Try all three and keep the smallest acceptable result.
No, it is a lossy encode. The canvas also works in 8-bit sRGB and writes no ICC profile, so a bitmap authored in a wide-gamut space will be read as sRGB. Colour-managed print files should not be routed through a browser canvas.
It depends on the version. Windows 11 reads AVIF once the AV1 Video Extension is installed, and macOS handles it natively from Ventura. Recent Photoshop releases support it, older installations refuse it, and many third-party viewers still do not know the format.

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