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Convert BMP to JPG

Files never leave your device. All processing happens in your browser.

Lower means a smaller file. Above 90 the file grows fast for little visible gain.

Pixels. Leave empty to keep the original dimensions.

JPG has no transparency, so see-through areas are filled with this colour.

How to convert BMP to JPG

  1. 1

    Drop in your BMP files, however large they are.

  2. 2

    Choose a quality level — 85 is a safe default.

  3. 3

    Look at the size reduction, then download.

BMP files are big because they barely compress at all. A bitmap stores three bytes for every single pixel, in order, with almost no cleverness applied. A 4000 × 3000 image therefore takes about 36 MB regardless of what it depicts — a photograph and a plain white rectangle cost exactly the same. Converting to JPEG typically removes 90–98% of that.

Where BMPs still come from

Almost nobody chooses BMP deliberately any more, which is why encountering one is usually a sign of specific equipment or old software. Windows Paint saved BMP by default for years. Many flatbed scanners, industrial cameras, microscopes and medical imaging devices still export it because it is trivial to write and involves no compression decisions. Screen capture utilities from the XP era produced it. Some CAD and GIS exports still offer it as the safe option.

What you gain and what you give up

BMP is lossless, so this conversion is the one point where quality is genuinely traded away. Unlike converting a JPG or a WebP, you are starting from pristine data — which is good news, because JPEG performs at its best on a clean source. There are no pre-existing artifacts for it to preserve or amplify, so a quality setting of 85 on a BMP gives a noticeably better result than the same setting applied to an already-compressed file.

  • For scanned photographs and camera output, quality 85 is usually indistinguishable from the original at normal viewing size.
  • For scanned documents and anything with fine text, use 92 or higher — JPEG softens hard edges and small lettering suffers first.
  • For scientific or measurement imagery where exact pixel values matter, do not use JPEG at all. Convert to PNG instead and keep every value intact.

Transparency, and why it rarely matters here

The BMP format does have a 32-bit variant with an alpha channel, but it is rarely used and inconsistently supported — many programs that write it are ignored by many programs that read it. If your BMP does carry transparency, JPEG cannot keep it, and those pixels are filled with the background colour you choose above.

A note on very large files

Because BMPs are uncompressed, they get big enough to strain a browser tab. A 100 MB bitmap has to be decoded into memory before it can be re-encoded, and on a phone that may simply fail. If a conversion gives up, that is a device memory limit rather than a fault in the file — try it on a desktop, or set a longest-edge limit to reduce the pixel count first.

Everything is processed in this tab on your own machine. For scanner output containing documents or medical images, that matters: no copy is created anywhere else.

Questions about BMP to JPG

Why are BMP files so enormous?

BMP stores each pixel individually with essentially no compression — roughly three bytes per pixel. The file size depends only on the dimensions, so a plain white image costs exactly as much as a detailed photograph of the same size.

How much smaller will the JPG be?

Usually 90 to 98 percent smaller. A 36 MB bitmap commonly converts to under 2 MB at a quality level most people cannot distinguish from the original.

Will I lose quality converting BMP to JPG?

Some, since JPEG is lossy and BMP is not. But because the BMP is a clean uncompressed source with no existing artifacts, JPEG performs unusually well on it. Quality 85 is typically indistinguishable at normal viewing size.

I am converting a scanned document. What quality should I use?

At least 92. JPEG blurs sharp edges, and small text is the first thing to suffer. For scanned text, PNG is often the better target because it keeps letterforms perfectly crisp.

My BMP is from a scanner or microscope. Is JPEG appropriate?

Not if the exact pixel values matter for measurement or analysis, because JPEG changes them. Convert to PNG instead, which compresses losslessly and preserves every value exactly.

The conversion failed on a very large BMP. Why?

Uncompressed bitmaps have to be fully decoded into memory before re-encoding, and a very large one can exceed what a browser tab has available — especially on a phone. Try on a desktop, or set a longest-edge limit to reduce the pixel count.

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