Convert BMP to JPG for a Much Smaller File
Convert BMP to JPG in your browser. A BMP is raw pixels with a header rather than a compressed image, which is why this is the conversion with the largest size reduction on the whole site.
Your images never leave your device
Nothing to delete later
Safe for instrument output
Works in every modern browser
How it works
- 1
Add your BMPs
Drop the files onto the page or click to browse and select them.
- 2
Set the quality
Choose how hard to compress — the default suits photographs, and screenshots want higher.
- 3
Download
Save the JPEG files individually or all at once as a zip.
Why use this tool
The biggest size drop there is
BMP applies no compression at all, so a photographic image typically loses ninety-five per cent or more of its bytes.
Row order handled correctly
BMP stores scanlines bottom-up by default, which is why some converters hand back an upside-down picture.
Ambiguous alpha resolved
The fourth byte of a 32-bit BMP may be transparency or may be padding, and guessing wrong renders the image invisible.
A colour profile at last
BMP almost never carries one, so the output can be tagged sRGB instead of leaving colour to whatever opens it.
No 36-megabyte upload
An uncompressed image is enormous, and sending it to a server is the slowest part of any hosted converter.
Nothing is uploaded
BMP comes out of instruments and industrial systems, so the picture itself is often the confidential part.
A BMP is not a badly compressed image — it is not compressed at all
This is the fact that explains everything else about the format. Most image formats store a compressed representation that has to be decoded before you can look at a pixel. A BMP in its ordinary form stores the pixels themselves, three or four bytes each, laid out in rows, behind a short header describing the layout. It is essentially a dump of what sits in video memory, which is exactly what it was designed to be when Windows introduced it in the nineteen-eighties. The arithmetic is therefore simple and brutal: a 4000 by 3000 image at 24 bits per pixel occupies thirty-six megabytes, and it occupies thirty-six megabytes whether it is a photograph, a screenshot or a completely white rectangle. Converting that to a JPEG at a sensible quality typically produces something between one and three megabytes. That is a reduction of ninety-five per cent or more, the largest ratio of any conversion offered here, and it is achieved not by clever encoding but simply by starting to compress at all.
BMP rows are stored bottom-up, and that is why images come out upside down
If you have ever converted a BMP somewhere and received a vertically mirrored picture, this is why, and it is not a corrupt file. When the format was designed, image data was written into a coordinate system whose origin sat at the bottom-left corner, so a BMP stores its scanlines starting from the bottom row and working upward — the opposite of essentially every format that came after it. Later the specification allowed the other order too, and it signalled which one by a sign: a positive height field means the rows are bottom-up, a negative height field means they are top-down. That is the whole mechanism. A reader that takes the absolute value of the height without checking the sign, which is an easy mistake and a common one, will flip half the files it meets. It is a good demonstration of why format details matter, because the resulting image is not subtly wrong or slightly degraded — it is simply upside down, and no amount of quality setting will address it.
Thirty-two-bit BMPs have an alpha channel that may not be an alpha channel
Here is the other classic BMP failure, and it produces a more alarming result than an upside-down photo. A 24-bit BMP uses three bytes per pixel for blue, green and red. A 32-bit BMP uses four — but the original BITMAPINFOHEADER never said what the fourth byte was for. In practice it was padding, present because aligning each pixel to four bytes is faster for the hardware, and it was very often filled with zeros. Later header versions, V4 and V5, added explicit channel masks that can declare the fourth byte to be alpha. So a converter meeting a 32-bit BMP has to decide, and if it guesses that the padding is alpha in a file where every one of those bytes is zero, it concludes that every pixel is fully transparent and produces an image that is entirely blank. People see this and assume the file is broken. The safe reading is to treat the fourth byte as padding unless the header explicitly declares an alpha mask, and that is what happens here.
Where BMP files still come from, which explains who needs this
BMP has been obsolete for general use since the nineteen-nineties, yet the files keep appearing, and it is worth naming the sources because they share a character. Windows Paint has always saved BMP and still offers it. Scanner drivers built on the older TWAIN interface commonly default to it. Industrial machine-vision cameras output raw frames as BMP because the format needs no encoder and adds no latency on a production line. Laboratory and medical instruments — spectrometers, gel imagers, microscope cameras — write BMP for the same reason. Older point-of-sale terminals, kiosk software, embedded firmware and some CAD packages export it. Pasting an image from the Windows clipboard into certain applications yields it. What all these have in common is that they are systems nobody is going to update: the equipment works, replacing it is expensive, and the output format was fixed years ago. Converting BMP is therefore almost always a legacy-integration job rather than a consumer one.
The one format on this site with nothing hidden inside it
Every other source format handled here carries baggage. A HEIC has GPS coordinates and a device serial. A JPEG from a camera has EXIF. A PDF has annotations and possibly text under a black box. A BMP has essentially none of it: no EXIF block, no orientation tag, no capture time, no location, no thumbnail, no author field. The header describes width, height, bit depth and layout, and after that the file is pixels. In one sense that is a small privacy advantage, since there is nothing to strip before sharing. In another it is a real limitation, because it also means no embedded colour profile. Nothing in a BMP says which red the red is, so every viewer assumes sRGB and hopes. If the file came from an instrument with a wide-gamut sensor, the colours have been quietly reinterpreted the whole time. Converting to JPEG is the first opportunity to attach a profile and state what the numbers mean.
The sensitive part of a BMP is the picture, not the metadata
That absence changes the shape of the privacy argument here, and it is worth following the change through. With most formats the worry is what is hidden in the file — the location where a photo was taken, the text under a redaction. A BMP hides nothing, so if the file matters it is because of what it plainly shows. And given where BMPs come from, that is frequently something you would not post: a frame from a machine-vision line showing a part and a defect, an image from a medical or laboratory instrument, a scan of a document made on old office equipment, a screen capture from a kiosk or a point-of-sale terminal, a diagnostic frame from embedded hardware. Uploading that to a hosted converter puts an image of your production line or your patient sample on somebody else’s disk, and does so slowly, because the file is thirty-six megabytes of uncompressed pixels. Here it is read from disk, decoded and re-encoded in the page, and no request is made — which you can confirm in the network panel while the batch runs.
How it compares
| Feature | This tool | Typical online converters |
|---|---|---|
| Images uploaded to a server | Never — converted in your browser | Usually uploaded |
| Handles bottom-up row order | Always | Often flipped |
| Treats padding as padding | Unless a mask says otherwise | Sometimes blanks the image |
| Tags the output sRGB | Yes | Rarely |
| Image-count limit | Unlimited | Often capped on free tier |
| Price | Free | Free / paid tiers |
Features
All common BMP variants
The classic header and the later V4 and V5 forms are read, along with 8, 16, 24 and 32-bit depths.
Bottom-up and top-down
The sign of the height field is respected, so rows come out in the order the file intended.
Adjustable quality
A visible slider, because a machine-vision capture and a scanned photograph want different settings.
sRGB tagging
The JPEG is written with a colour space declared, which the BMP it came from almost certainly lacked.
Batch conversion
Add a folder of BMPs and convert them in one pass without an upload queue.
No installation
Nothing to download or install — it runs on the web page.
Arabic and RTL friendly
Full interface in eight languages, including right-to-left Arabic.
Secure by default
Served over HTTPS, with no file tracking and no third-party upload.
Who uses it
Industrial and manufacturing teams
Turning raw machine-vision frames into files a reporting system will accept.
Laboratory and medical staff
Making instrument output small enough to attach to a record or a report.
Anyone with an old scanner
Converting the enormous BMPs a TWAIN driver produces by default.
Developers maintaining legacy systems
Bridging equipment that only emits BMP to software that only accepts JPEG.
Frequently Asked Questions
JPG uses efficient compression that produces small files, ideal for photographs and anywhere a compact, widely-supported image is needed. The whole conversion happens locally in your browser, so it is instant and private.
Yes. Use the quality slider from 1 to 100 — lower values make smaller files; around 85 is a good balance for most images. Note JPG has no transparency, so transparent areas become white.
No. The conversion runs entirely in your browser using the Canvas API — your images are never uploaded, stored, or shared.
Yes. Add as many BMP images as you like and convert them in one pass; download each result individually or all together as a ZIP.