Convert BMP to WebP
Output is typically about 94% smaller.
- Files stay on your device
- Free, no sign-up
Related tools
All image toolsQuestions
Can I convert a whole folder of BMP files at once?
Yes — add them all and each is processed in turn on your device. They are handled sequentially rather than in parallel so that a large batch cannot lock up a phone or a laptop; expect it to work steadily through the queue rather than finishing everything at once.
Will converting BMP to WebP make the file smaller?
Usually, yes. A 12-megapixel photo is around 36 MB as BMP and around 2.1 MB as WebP — about 94% smaller. Because WebP is lossless the result depends entirely on the image content — flat colour and text compress far better than photographic detail.
Does converting BMP to WebP lose quality?
A little, by design. BMP is lossless and WebP is lossy, so some detail is discarded in exchange for a much smaller file. At quality 80–90 the result is visually indistinguishable from the original for photographs. For screenshots, logos or anything with sharp text, stay with a lossless format instead — lossy compression creates visible halos around hard edges.
Is transparency preserved when converting BMP to WebP?
Yes. Both BMP and WebP support an alpha channel, so transparent and semi-transparent pixels carry across unchanged — a logo with a cut-out background stays cut out, and soft drop shadows keep their gradient rather than picking up a white halo. Because WebP can compress lossily, a very hard edge against transparency may pick up slight softness at high compression; keep quality at 85 or above for cut-out graphics.
Why are BMP files so large?
BMP stores pixels essentially uncompressed — three or four bytes per pixel with no encoding at all. A 12-megapixel photo therefore lands around 36 MB, roughly 11× the same image as a JPEG. That simplicity is deliberate: legacy Windows software and embedded devices can read BMP with almost no code.
How it works, and more about bmp to webp
How it works
- Add your BMP file. Drag a BMP file onto the drop zone, or click to browse. You can select several at once.
- Choose your settings. Adjust the quality slider if you want a smaller file or a sharper result. 80 suits most photographs.
- Download the WebP. Conversion runs on your device as soon as each file is added — no upload, no queue. Download each result when it is ready.
Why people convert BMP to WebP
Putting legacy assets on the web — usually a batch of old bitmaps that need to become page-ready without a manual pass through an editor.
The biggest size win of the three targets, and it keeps transparency where the BMP variant had it. Sensible for a bulk migration of old artwork.
Worth knowing: Check that the BMP is not an 8-bit palettised variant that already lost colour before you got to it. WebP will faithfully preserve a limited palette rather than restoring what was thrown away.
BMP and WebP side by side
| BMP | WebP | |
|---|---|---|
| Full name | Bitmap Image File | WebP |
| Compression | Lossless | Lossy or lossless |
| Transparency | Yes — alpha channel | Yes — alpha channel |
| Animation | No | Yes, in the format |
| Browser support | Supported in all major browsers, though rarely used on the web | All modern browsers — Chrome 32+, Firefox 65+, Safari 14+ (2020), Edge 18+ |
| Typical 12 MP photo | ~36 MB | ~2.1 MB |
| Usually used for | Legacy Windows applications, scanners and embedded displays | Web images where page weight matters and modern browsers are the audience |
On a typical 12-megapixel phone photo, the WebP output comes out about 94% smaller than the BMP original. These are order-of-magnitude figures for one kind of image — your own results will vary a great deal, because flat colour, text and line art behave nothing like photographic detail, and the quality slider moves the figure substantially.
What this tool actually produces
Not estimates. Each row below was produced by running the file through this page in a real browser and measuring the result, at the default quality of 82.
| Test image | BMP in | WebP out | Change |
|---|---|---|---|
| UI screenshot 1440 × 900, dense text on flat panels — the hardest case for JPEG | 3.7 MB | 47 KB | -99% |
| Line-art diagram 1200 × 800, hard edges and large flat areas | 3.7 MB | 10 KB | -100% |
Every test image got smaller, though by very different margins — flat colour and text behave nothing like photographic detail, so treat the closest row to your own content as the useful one. Measured in Chrome 150.0.7871.46; other browsers encode slightly differently.
What to watch out for
- Not accepted by some older desktop software and print workflows
- Slightly slower to encode than JPEG
- Larger than AVIF at the same quality
About the two formats
BMP stores pixels essentially uncompressed, which makes it enormous — a 12-megapixel photo lands around 36 MB, roughly 11× the same image as a JPEG. It persists mainly inside legacy Windows software, scanning utilities and embedded systems where decoding simplicity beats file size.
WebP is the pragmatic modern choice for the web: roughly 25–35% smaller than JPEG at comparable quality, with transparency and animation that JPEG lacks, and — since Safari 14 in 2020 — support in every browser that matters. It is the format to reach for when you want smaller pages without worrying about fallbacks.
Other conversions
Everything runs on your device — nothing is uploaded, so there is no size limit, no queue and no copy left on a server afterwards. There is more on how browser-based conversion works if you want the detail. Otherwise, browse every image tool, or convert WebP back to BMP.