Introduction
You spent a weekend scanning old family photos with a flatbed scanner, and every file came out as a BMP. Now you have 200 files at 5 megabytes each, eating up a gigabyte of storage, and you cannot easily share them or upload them to a photo service. BMP is the default output for many older scanners on Windows, but it is a terrible format for archival and sharing. Converting those scanned BMPs to JPG shrinks them by 90 percent and makes them usable on any device. In this guide we cover why scanners still output BMP, three ways to batch convert scanned photos, and how to build a clean digital archive.
Why This Happens
Scanners output BMP for historical reasons. When flatbed scanners became popular in the 1990s, Windows used BMP as its native image format, and scanner software defaulted to it for maximum compatibility. Many scanner drivers, especially older ones and those bundled with all-in-one printers, still default to BMP even today. The problem is that BMP is uncompressed, so a 300 DPI scan of a 4x6 photo is about 4 megabytes, and a 600 DPI scan is 16 megabytes. For a box of 200 old family photos, that is 800 megabytes to 3 gigabytes of storage, all in a format that modern phones and web platforms handle poorly. JPG, on the other hand, uses lossy compression designed for photographs and can shrink those same scans to 200 to 500 kilobytes each, with no visible quality loss at high settings. The result is a folder 90 percent smaller that opens on every device.
3 Solutions
Solution 1: Use an online batch converter for instant results. The piczen image converter handles BMP to JPG batches right in your browser, with no software install and no signup. You drag in a folder of BMP scans, pick JPG as the output, set quality to 85 or 90, and download a zip of compressed files in a couple of minutes. This is the fastest path for most users, since it works on any operating system, requires no setup, and processes hundreds of files in a single pass. The tradeoff is that very large batches, say 500 or more scans, may hit browser memory limits, so split huge folders into batches of 200 or so.
Solution 2: Change your scanner software to output JPG or TIFF for future scans. Most scanner drivers, including the software bundled with Epson, Canon, and HP all-in-one printers, let you pick the output format in the settings. Switching to JPG prevents the problem from happening again on future scans, so you never have to convert another batch. For archival masters where you want zero quality loss, choose TIFF instead, which is lossless like BMP but more widely supported and more efficiently compressed. The one-time setup takes about two minutes, and it saves you hours of conversion work down the road.
Solution 3: Use IrfanView or XnConvert on Windows for very large folders. Both are free desktop tools that batch-convert BMP to JPG quickly, and they handle folders with thousands of files without the memory limits of a browser. IrfanView is lightweight and fast for simple conversions, while XnConvert offers advanced options like resizing, renaming, and color adjustment in the same batch. The tradeoff is that both require a download and install, and they only run on Windows, so Mac users should stick with online tools or use the built-in Automator app for batch conversions.
Step-by-Step Guide
For converting your existing BMP scans, open the image converter in any modern browser. Drag your BMP files from your scans folder onto the page, you can select hundreds at once. Set the output format to JPG and pick a quality of 85 or 90, which gives an excellent balance of file size and visible quality for scanned photos. Quality 90 is nearly indistinguishable from the original BMP, while quality 85 cuts file sizes a bit more and is still sharp enough for sharing and viewing on any screen. Click Convert and let it process, a batch of 200 BMP scans usually takes a couple of minutes depending on your upload speed and the server load. When it finishes, download the zip, extract it, and you have a folder of JPGs that are roughly 90 percent smaller than the originals. Spot-check a few images at full zoom to confirm the quality, then rename the files with descriptive names like 1985-beach-vacation-01.jpg for easy searching later. Upload the JPGs to Google Photos, iCloud, or your preferred cloud service for easy sharing with family. Keep the original BMPs on an external drive as lossless masters if you want maximum archival quality, and consider also converting a set to TIFF as a long-term archival format that is more widely supported than BMP.
Pros and Cons
Converting scanned BMPs to JPG reclaims enormous amounts of storage and makes old photos shareable for the first time. A 3 GB folder of BMP scans often shrinks to under 300 MB as JPGs, with no visible difference at quality 90, which means you can finally email them, upload them to cloud services, and share them with family who would never be able to open a BMP on their phone. JPG also opens on every device and photo service, while BMP support is inconsistent on modern phones and web platforms, so the conversion solves a real compatibility problem, not just a storage problem. The tradeoff is that JPG is lossy, so there is a small quality loss on each conversion, and re-saving a JPG repeatedly degrades it further through generation loss. For archival purposes, you should keep the BMP originals or convert to a lossless format like TIFF for master copies, and only use JPG for sharing, viewing, and everyday use. For most families, the smaller, shareable JPGs become the working archive, since family members never look at the original BMPs anyway, and the convenience of cloud sharing far outweighs the tiny quality difference that is invisible on any screen smaller than a 4K monitor.