BMP to JPG Converter

How do you turn a BMP into a JPG and check the result?

Choose a BMP file, wait for automatic conversion, and click Download to save its JPG version. Start with the default 92% Quality setting, then compare the single-image before/after preview and the displayed file sizes. For several images, select them together and use Download ZIP after reviewing the batch results.

For a worked example, choose a file named scan.bmp that is 4,000,000 bytes. The default quality becomes 0.92 for the browser encoder, and the derived output name is scan.jpg. Suppose the resulting JPEG measures 600,000 bytes: the single-image size change is rounded from (600,000 − 4,000,000) ÷ 4,000,000 × 100 to −85%. These output bytes illustrate the calculation, not a prediction of your scan's compression. A different image can produce a different size at the same setting.

Changing Quality on a single image schedules another conversion from the original file after a short delay. Wait for it to finish before downloading. This lets you compare settings without repeatedly converting a previously compressed JPEG. Keep the original BMP alongside the downloaded copy if you expect to make more edits later.

What is BMP, and when is JPG the useful alternative?

BMP is a bitmap image format associated with Windows. Many BMP files store uncompressed pixel data, although BMP also has compressed and palette-based variants. A file's dimensions alone therefore do not establish its exact byte size: headers, color depth, row padding, and encoding also matter. The converter reads the actual source file size rather than estimating it from width and height.

JPG and JPEG name the same image format. This tool requests image/jpeg output and gives BMP conversions a .jpg extension. JPEG is useful for photographic copies intended for attachments, presentations, or web content when some loss of detail is acceptable. Text-heavy scans, diagrams, and pixel art deserve closer inspection because compression can affect sharp boundaries.

Choosing between an original BMP and a converted JPG

Concern	BMP original	JPG output here
File size	Depends on BMP encoding and content	Depends on selected quality and browser encoding
Exact pixels	Retains your source data	Lossy re-encoding changes pixel values
Transparency	Depends on the BMP variant and decoder	Opaque; detected alpha gets a chosen background
Dimensions	Source width and height	Decoded dimensions; no resize controls on this page

How does JPEG quality change the image?

The quality conversion helper rounds and clamps the setting to 10–100, then divides it by 100 for encoding. The initial 92 becomes 0.92; it does not mean that the output keeps exactly 92% of the original information or becomes 92% smaller. There is no reliable formula that turns this percentage and the BMP byte count into a final JPEG size.

Conventional lossy JPEG, described by ITU-T T.81, uses an 8 × 8 discrete cosine transform and quantization. Quantization trades detail for more compact encoding. The browser controls the encoder details here; this page does not expose chroma subsampling or progressive encoding switches. At 100%, output still is not a lossless copy of the BMP.

Inspect small lettering, fine patterns, and edges as well as broad areas of the image. Lower the setting gradually if your priority is fewer bytes. If you also need to reduce pixel dimensions, use Image Resizer separately. For further compression work, open Image Compressor; this page does not expose a target file-size field.

How are transparent BMP pixels handled?

The tool checks the browser-decoded image for alpha values below 255. When it detects transparency, Background color appears and starts at white (#ffffff). Presets include black, light gray, dark gray, cream, and pale blue; a custom color picker is also available. The selected color fills the canvas before the image is drawn, producing an opaque background in the JPEG.

Detection has a limit: for images above 500,000 pixels it samples every fourth pixel. Sparse transparency can therefore escape detection. Browser support for a BMP variant also determines which pixels reach the canvas. Check the result rather than assuming every 32-bit BMP contains usable transparency. Keep the original when alpha matters; JPG to PNG cannot restore transparency or detail already flattened into a JPEG.

How do batch settings and ZIP downloads work?

Multiple selected files open the batch layout. It retains the first 50 files and converts queued items one after another. Each row shows source and output sizes when conversion succeeds. Use a file's settings button to set its Quality override, then Done to close the dialog. Clear override returns that file to the global settings.

Unlike single-image adjustments, batch setting changes require Re-convert All; its label includes the number of converted files. Use it before downloading results with your new settings. Each successful row has an individual download action. Download ZIP collects successful outputs into converted-jpg.zip; failed items are excluded. Review errors and keep the source files available rather than treating a downloaded archive as proof that the entire batch succeeded.

Why might a BMP fail, and what stays on your device?

Decoding uses createImageBitmap, so a BMP must be supported by your browser. The tool does not implement its own decoder for every bit depth or compression variant. An empty file fails validation, and decoding or canvas export errors return a conversion failure. Large images also need decoded pixel and canvas memory, so try fewer files together if a large batch is troublesome.

The picker advertises up to 100 MB per file, but that text is not a guarantee of successful decoding or a universal browser memory limit. Local files are processed through browser APIs without a conversion-server upload. The separate Fetch & Convert URL option does make a network request and requires an image response; remote access restrictions can prevent it from working. Download the source yourself and choose the local file if URL loading fails.

Finally, BMP metadata is not copied through the JPEG EXIF transfer path. That path requires an image/jpeg source, while the EXIF summary reader also expects a JPEG signature. Keep the BMP when you need its original metadata, exact pixel values, or an archival master. The JPG is a convenient derived copy rather than a replacement for every original.