Somewhere on an old drive, a legacy Windows machine, or the output folder of a piece of lab equipment, there is a stack of BMP files taking up far more space than they should. BMP is one of the oldest raster formats still in circulation — Microsoft Paint saved to it by default for years, and plenty of industrial cameras, scanner utilities, and in-house Windows tools still write it. The format stores every pixel raw and uncompressed, which is why a single photo-sized BMP can weigh tens of megabytes.
For photographs and screen captures you intend to share, JPEG is the obvious destination. It is the one image format that works absolutely everywhere — every phone, browser, upload form, and photo service accepts it — and its lossy compression routinely cuts a raw bitmap down to a small fraction of its original size while leaving photos looking essentially unchanged at sensible settings.
This converter does the work directly in your browser. The BMP is read and re-encoded on your own device through WebAssembly; nothing is transmitted anywhere, no account is needed, and the engine — a one-time download of about 5 MB — is cached by your browser, so later conversions start instantly. A quality slider lets you decide the size-versus-fidelity trade: the default of 85 keeps photos looking clean while producing small files, and lower values squeeze harder when you are fighting an attachment limit or a strict upload form. You can optionally strip metadata from the output as well.
One honest caveat before you work through a whole folder: JPEG is built for photographic content. Screenshots full of crisp text, line drawings, and flat-color diagrams can pick up faint smudging around hard edges, because that is exactly where lossy compression struggles. For those images, converting BMP to PNG instead keeps every edge perfectly sharp and still shrinks the file substantially.
Why convert BMP to JPEG?
- JPEG typically shrinks an uncompressed BMP to a small fraction of its size, freeing disk space and making files easy to send
- JPEG is accepted by every upload form, email client, phone, and photo service you will encounter
- A quality slider — defaulting to 85 — lets you balance file size against fidelity for each image
- Conversion happens in your browser, so old family photos and work captures are never uploaded anywhere
- Optional metadata stripping cleans the output before you share it
How it works
- Step 1
Drop your files
Drag your BMP files into the converter above, or click “Choose files”. Batches are welcome.
- Step 2
Pick your settings
JPEG is preselected. Adjust quality or size if you want, or keep the defaults.
- Step 3
Convert and download
Conversion runs locally in your browser. Download files individually or grab everything as a zip.
Frequently asked questions
- How much smaller will the JPEG be than my BMP?
- Substantially. BMP stores pixels with no compression at all, while JPEG at the default quality of 85 commonly compresses photographic images by a factor of ten or more. The exact ratio depends on the image content and the quality you choose, but a multi-megabyte BMP photo turning into a JPEG of a few hundred kilobytes is a normal outcome.
- What quality setting should I pick?
- The default of 85 is a solid all-purpose choice — photos look clean and files stay small. Push toward 90-95 if the image will be printed or closely inspected, and drop lower when file size matters more than fine detail, such as attachments with hard limits. Because JPEG is lossy, it is worth converting once at a higher setting rather than re-saving repeatedly, since each re-encode compounds the loss.
- Is this converter actually private, or does it process files on a server?
- It is genuinely local. The encoder runs as WebAssembly in your browser tab, so your BMP never leaves your device — there is no upload, no processing queue, and no server that ever sees the image. The only thing that ever comes down the wire is the engine itself, fetched once and cached by your browser.
- Why do text and sharp lines look slightly fuzzy after converting?
- That is JPEG compression doing what it does: it discards detail the eye tends not to notice in photographs, but hard edges — text, UI elements, line art — are where the discarded detail becomes visible as ringing or smudging. Raising the quality slider reduces the effect, but for screenshots and diagrams the better fix is converting to PNG, which is lossless and handles that content type far better.