BMP to WebP Converter
Drop BMP files, get web-ready WebPs back — 100% in your browser. No uploads, no accounts, no limits. Batch convert, genuine lossless option, transparency kept.
100% in-browserNo uploadsFree · no accountBatch up to 20 filesGenuine lossless optionTransparency kept
Windows screenshots, logos and diagrams saved as BMP are pixel-perfect but huge — and many apps, forms and the web only accept WebP. WebP is the modern web format: typically 25–35% smaller than PNG or JPG at quality 85, and it keeps transparency — but it is lossy unless the Lossless toggle is on.
Drop BMP files here
or — multiple files welcome
Up to 25 MB per file · up to 20 files per batch · nothing ever uploads
Your BMP is decoded by pure JavaScript built into the page — no decoder download, no waiting.
Loading the WebP encoder…
Privacy proof — verify it yourself
This page processes your images entirely on your device. Your file data never leaves the device — the only third-party requests are the site’s own analytics, which load at page open and never see your files.
External requests while you use this page: 0 (zero — as it should be)
- Press F12 to open developer tools, then open the Network tab.
- Drop a BMP file above and let it convert.
- Watch the Network tab: no file uploads while it works — the only requests are the site’s analytics, which load at page open. The counter above shows the same number live.
How to convert BMP to WebP without uploading it
- Drop your BMP files above — or paste one straight from your clipboard. You can add up to 20 at once.
- Pick a quality and width (quality 85 and 800 px are good defaults for the web; Original keeps every pixel). Turn Lossless on when every pixel must survive exactly. Each BMP becomes one still WebP.
- Download each WebP, or grab everything as one ZIP. Your originals are untouched and your file data never leaves your device.
Why convert BMP to WebP at all?
BMP is the format Windows Paint and many scanners save by default because it keeps every pixel — but that makes files huge, and many upload forms, email clients, messaging apps, websites and older programs only accept web formats. WebP is the modern web format: the same image is typically 25–35% smaller than PNG or JPG at quality 85 with no visible difference, it keeps transparency, and every modern browser displays it. That weight is time your visitor waits — especially on a phone — which is why switching a site's BMPs to WebP is one of the cheapest PageSpeed wins there is. Keep the BMP as your master copy for editing, and publish the WebP.
Lossy or lossless — which should you pick?
Pick lossy (the default, quality 85) when the image is going on a website, into a blog post, or onto Discord or a forum: it is the small file that loads fast, and at quality 85 it looks identical to the original for almost every photo — typically 25–35% smaller than the same image as PNG or JPG. Pick lossless when every pixel has to survive exactly — a master you will edit further, or an image with razor-sharp edges. Lossless files are bigger, sometimes bigger than the BMP for scans with large flat areas, because lossless cannot throw detail away. Either way, keep the BMP as your master copy and publish the WebP.
Honest limitations
- WebP is lossy unless Lossless is on — the output discards some detail. Quality 85 is visually identical to the original for most photos, but quality 100 is near-lossless, not pixel-perfect. Keep the BMP as your master copy.
- Lossless WebP is usually much smaller than the BMP but larger than a lossy WebP of the same image — lossless cannot throw detail away, so for photos it can come out bigger than a lossy WebP. If the file comes out bigger than the BMP, the card says so — use lossy mode for publishing instead.
- Fully transparent pixels keep their transparency, not the colour underneath — libwebp discards the RGB stored under alpha-0 pixels. Nothing can see that colour, so nothing is lost visually, but a lossless round-trip will not reproduce it.
- RLE-compressed BMPs are refused — a few old apps saved BMPs with RLE8 or RLE4 compression. This tool refuses them with a clear message; re-save uncompressed (24-bit BMP in Paint) and try again.
- BMP is a still format — a BMP holds exactly one picture, so every output is one still WebP. Nothing is animated, and nothing is silently dropped.
- BMP carries no EXIF and no orientation — there is no metadata to keep and nothing to rotate. DPI is dropped by the re-encode, so the WebP carries no DPI value even when the BMP had one.
- 16-bit BMPs are decoded to 8 bits per channel — WebP only stores 8 bits per channel, so the extra depth is gone. On a standard display the result looks the same, but keep the original if you need the depth.
- "Typically 25–35% smaller" is scoped to PNG/JPG comparison only — it compares a lossy WebP at quality 85 with the same image as PNG or JPG. It is never a guarantee, and it is never claimed against the BMP itself, which is uncompressed and almost always far larger than the WebP.
- Estimates are estimates — the size shown while converting is a rough model; the real size is shown once conversion finishes.
Frequently asked questions
How can I convert BMP to WebP without uploading it anywhere?
This converter runs entirely in your browser: it decodes your BMP with a pure JavaScript decoder built into the page and re-encodes it as WebP with the libwebp encoder running on your device. Your file data never leaves the device — the only third-party requests are the site's own analytics, which load at page open and never see your files. Verify it in the Network tab while it works.
Why is my BMP file so large?
BMP is an uncompressed format — every pixel is stored in full, so a BMP is typically much larger than the same image as WebP, PNG or JPG. Converting to WebP shrinks it dramatically, because WebP predicts neighbouring pixels and packs the result far tighter than raw BMP data. A photo BMP that is 15 MB on disk often becomes a WebP of a few hundred kilobytes at quality 85, and the tool shows the before and after size honestly for every file.
Is the WebP output lossless?
Only when the Lossless toggle is on. With it on, the encoder is libwebp's true lossless mode, which stores every pixel exactly — a lossless WebP decodes back to the identical image. The one exception is fully transparent pixels: they keep their transparency exactly, but the colour stored underneath them (which nothing can see) is discarded by the encoder. With the toggle off (the default), the output is lossy WebP at the quality you pick: quality 85 looks identical to the original for most photos, and quality 100 is visually near-lossless but not pixel-perfect. Keep your BMP as the master copy and use WebP as the published version.
Does the WebP keep transparency?
Yes. WebP stores an alpha channel, so transparency in a 32-bit BMP stays transparent in the WebP — the preview shows it against a checkerboard so you can see it. That is an advantage over GIF, which flattens transparency onto a background colour, and over JPG, which has no transparency at all. A 32-bit BMP whose alpha byte is 0 everywhere is treated as opaque, because that is an unused alpha channel, not a transparent image.
Will my BMP animate as a WebP?
No. BMP is a still-image format — a BMP file holds exactly one picture, with no frames and no timing information, so there is nothing to animate. Every output of this tool is one still WebP per file. If you want a moving WebP, convert several BMPs here and combine the WebPs elsewhere, or use a tool that stitches multiple still images into one animated WebP.
What BMP files can this converter not open?
RLE-compressed BMPs (RLE8 and RLE4) are not supported — most BMPs are uncompressed, but a few old apps saved them compressed, and this tool tells you plainly instead of failing silently. Files that are only named .bmp but are really PNG, JPG or GIF are also refused with a clear message. Corrupt, empty and oversized files are refused the same way.
Can I make the WebP fit under an upload limit?
Yes — pick a destination preset (website hero aims for under 300 KB, blog image under 150 KB, Discord or forum under 256 KB) and the converter retries with smaller width and lower quality until it fits, or reports the smallest size it could reach. A target is an aim, never a guarantee — the tool reports the size it actually reached on each file. If Lossless is on, the fit loop switches to lossy first, because a lossless file cannot be shrunk by lowering quality.
What happens to bit depth, DPI and metadata?
The decoder reads 1, 4 and 8-bit paletted BMPs, 16-bit 555/565 BMPs, and 24/32-bit BMPs, top-down or bottom-up, and every image is converted to 8 bits per channel, because WebP only stores 8 bits per channel — the difference is invisible on a standard display, but keep the original if you need the extra depth. BMP carries no EXIF metadata at all, so there is nothing to keep, and DPI is dropped by the re-encode — the WebP carries no DPI value even when the BMP had one.
Is WebP really smaller than BMP?
Almost always, by a lot — a BMP stores every pixel uncompressed, so even a lossless WebP is usually far smaller than the BMP it came from, and a lossy WebP at quality 85 is typically 25–35% smaller than the same image as PNG or JPG. The tool shows the before and after size honestly for every file, so you can see the saving instead of taking our word for it. If a file ever comes out bigger, the card says so and you can keep the BMP.
Is there a file size or daily limit?
No daily limit, no account. A 25 MB cap per file and 20 files per batch apply, because browsers cannot safely hold larger images in memory. Very large BMPs are also limited to 50 megapixels for the same reason.
How do I verify my files really never upload?
Open developer tools (F12), go to the Network tab, then convert a file. Your file data never leaves your device — the only third-party requests are the site's own analytics, which load at page open and never see your files. The live counter above shows the same number.