Where BMP Photos and Scans Come From
BMP is rarely chosen on purpose for photos, yet plenty of them end up as bitmaps. They usually come from equipment and software that values simplicity over file size.
Scanners
Many scanner utilities offer BMP as a default or first option because it needs no compression settings. A single A4 page scanned in colour at 300 DPI is roughly 25 MB as a bitmap.
Lab, Industrial and Medical Cameras
Microscope cameras, inspection systems and some medical devices write BMP because every pixel is stored exactly as captured, with nothing to decode. That suits the device; it does not suit an email.
Older Windows Programs
Paint, screen-capture utilities and many legacy applications saved BMP by default for years. Archives of family photos scanned in the 1990s and 2000s are often full of them.
Check the scanner's own settings
Most scanner software can save straight to JPG or PNG. If you scan often, switching its default format saves this step and keeps very large scans under the 20 MB limit of this page.
How to Convert BMP to JPG in 3 Steps
Drop your BMP files
Drag one or more .bmp files onto the dashed area, or click to browse. They are read in your browser and never uploaded.
Choose the quality
JPG is selected and Quality starts at 90%, a safe choice for photos and scans. Lower it only if you need a smaller file.
Download the JPG files
Click Download next to each file, or Download All as ZIP. Every result shows how much smaller the JPG is than the bitmap.
Drop one or more BMP files.
Pick JPG and a quality setting.
Download each JPG or all of them as a ZIP.
How Much Smaller Does a BMP Get as JPG?
A bitmap photo stores three bytes for every pixel, whatever the picture shows. A 12-megapixel photo is therefore about 36 MB as a BMP.
What JPG Does Differently
JPG analyses the image in small blocks and keeps the detail your eye notices while discarding what it does not. Converting BMP to JPG at 90% quality typically shrinks a photo by 90–95% with no difference you can see at normal viewing size.
For comparison, the same photo saved as a lossless PNG is often still more than half the size of the BMP, because camera noise does not compress well without loss. That is why JPG is the format for photos.
Why the Saving Varies
Busy photos with fine texture, such as foliage or gravel, need more data than smooth skies and studio backgrounds. Each result in the list shows the actual saving for that file.
Resolution matters as much as format
A scan at 600 DPI has four times the pixels of one at 300 DPI. If the picture is only going to a screen, reducing its dimensions with resize image shrinks the JPG further than any quality setting.
Choosing the Right JPG Quality
The quality slider sets how much detail JPG keeps. The best value depends on what is in the picture.
Photos
For photographs, 80–90% looks the same as the bitmap to almost everyone. 90% is the default because it leaves a safety margin for printing and later cropping.
Scanned Documents and Text
Sharp black text on white paper is where JPG struggles most: lower settings leave grey smudges around letters. Keep scans of documents at 90% or above, or convert them to PNG instead, which keeps every edge perfectly sharp.
Greyscale and black-and-white scans
Pages scanned in greyscale or pure black and white often arrive as 8-bit or 1-bit bitmaps. As PNG they stay small and razor-sharp, so for paperwork PNG usually beats JPG on both size and clarity.
Need a hard size limit?
Convert at 90%, then use compress to 200 KB or compress JPEG, which find the best quality under a target size.
Getting a Bitmap Through Email and Upload Limits
Email services and web forms rarely accept files of tens of megabytes, and many portals reject BMP outright.
Most email services cap attachments at around 20–25 MB per message. One scanned page as BMP can use all of that; as JPG it takes a small fraction, so a whole set of pages fits in one message.
Forms and Portals
Application portals typically accept JPG and PNG with limits between 100 KB and 5 MB. After converting BMP to JPG, check the requirement and, if needed, resize the image to the requested dimensions.
Printing
Print shops and photo kiosks accept JPG everywhere. At 90–95% quality and the original resolution, a print made from the JPG cannot be told apart from one made from the bitmap.
BMP vs JPG at a Glance
| BMP | JPG | |
|---|---|---|
| Compression | Usually none | Lossy, adjustable |
| 12-megapixel photo | About 36 MB | A few megabytes or less |
| Photo quality | Exact | Visually identical at 90% |
| Accepted by websites and email | Rarely | Almost everywhere |
| Best for | Device output and raw storage | Sharing, uploading, printing photos |
When Not to Convert BMP to JPG
JPG is the right home for photos and scanned pictures, but it is the wrong one for some bitmaps.
Screenshots, Icons and Line Art
Flat colours and hard edges are exactly what JPG blurs. Text picks up halos and solid areas show faint blocks. For these, BMP to PNG keeps every pixel and still shrinks the file dramatically.
Images You Will Edit Again
Every time a JPG is edited and saved, it loses a little more detail. If you plan further edits, keep a PNG master and export JPG copies for sharing.
Medical and scientific images
Images used for measurement or diagnosis should stay lossless. JPG changes pixel values slightly even when the picture looks identical, so keep those as PNG or as the original bitmap.
After You Convert BMP to JPG
To meet a strict limit, use compress to 200 KB; to combine pages, use image to PDF. Resize image sets exact dimensions.
For screenshots and graphics, see BMP to PNG. All other format pairs are in the image converter.