BMP to WebP Converter
Convert BMP to WebP in your browser. BMP files usually come from Windows Paint, legacy Windows programs, embedded displays and some scanners; WebP is the better fit for images on websites and in apps. You get a lossy WebP at the quality you choose (lossless under More options), keeping transparency. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
BMP expected · other image formats also work
How to use BMP to WebP
- 1
Add your BMP files: drop them here, choose them, or paste from the clipboard.
- 2
Set the quality. 80 to 85 is visually close to the original for most photos.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .webp files one at a time or together as a ZIP.
Why use Aback Images for bmp to webp
Where the WebP goes next
WebP opens in every current browser, Windows, macOS, Android, and recent Photoshop, GIMP and Affinity.
WebP next to BMP
A lossy WebP usually comes out far smaller than the BMP, which stores usually none; RLE for some 4 and 8-bit files.
The first lossy pass
The BMP holds 1, 4, 8, 16, 24 or 32 bits per pixel with nothing discarded yet. This conversion is the first lossy encode these pixels see, and hard edges and flat colour show it first.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
BMP vs WebP
What changes from BMP to WebP
Encoding: the BMP uses usually none; RLE for some 4 and 8-bit files; WebP uses lossy VP8 coding or lossless VP8L, and the download is a lossy WebP at the quality you choose (lossless under More options), keeping transparency.
Bit depth: 1, 4, 8, 16, 24 or 32 bits per pixel in the BMP; WebP allows 8 bits per channel, and the WebP written here has 8 bits per channel.
Colour: RGB or an indexed palette in the BMP; WebP supports RGB; lossy WebP stores colour at half resolution (4:2:0), written here as 8-bit sRGB.
Transparency: the BMP stores it as an optional fourth byte in 32-bit files, which many programs ignore; the WebP keeps it as a separate alpha plane, available in lossy as well as lossless files.
Metadata: the BMP can carry nothing beyond the header's resolution fields (and a colour profile in rare V5 headers); WebP can carry EXIF, XMP and ICC chunks, but nothing is copied across.
About BMP
BMP stores raw, uncompressed pixels. Files are huge but trivially simple, which is why some legacy Windows software, embedded displays and printers still ask for it.
A BMP is a 14-byte file header ('BM' and the offset to the pixels), a DIB header (40 bytes, or 108 and 124 bytes in the V4 and V5 versions that add colour masks and alpha), an optional palette, then pixel rows padded to 4 bytes and normally stored bottom-up.
BMP files usually come from Windows Paint, legacy Windows programs, embedded displays and some scanners.
About WebP
WebP is Google's web image format. It supports lossy and lossless compression, transparency and animation, and is typically 25 to 35 percent smaller than JPEG at the same visual quality.
A WebP is a RIFF file: 'RIFF', a length, 'WEBP', then chunks. A simple lossy file is one VP8 chunk and a lossless one is VP8L; the extended VP8X header announces alpha, animation, ICC, EXIF or XMP chunks.
When converting BMP to WebP makes sense
WebP is the better choice for images on websites and in apps, while BMP suits legacy software and embedded systems that require it.
WebP strengths: 25-35% smaller than JPEG; Transparency and animation in one format; Supported by every modern browser. Drawbacks to weigh: Some older desktop apps and photo printers cannot open it; Max 16383 px per side.
Limitations
- BMP stores nearly every pixel literally, so almost any compressed target is several times smaller.
- A 32-bit BMP can carry an alpha byte that most programs ignore; if the image suddenly gains transparent areas after converting, that byte was set.
- A few older desktop apps, print services and upload forms still reject WebP; keep a JPG or PNG copy for those.
- WebP images are limited to 16383 pixels on each side.
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Frequently asked questions
Does converting BMP to WebP lose quality?
WebP is lossy, so detail the eye barely notices is discarded to save space.
Is transparency kept in the WebP?
Yes. BMP stores it as an optional fourth byte in 32-bit files, which many programs ignore, and the WebP is written with an alpha channel, so transparent areas stay transparent.
What quality should I choose for WebP?
80 to 85 is visually close to the original for most photos. Go lower for thumbnails, or switch on Lossless under More options for screenshots and graphics.
Which apps open WebP files?
Every current browser, Windows, macOS, Android, and recent Photoshop, GIMP and Affinity.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.